MORTGAGE LOAN SALE AND ASSIGNMENT AGREEMENT, DATED

Exhibit 99.1

TERWIN ADVISORS LLC,

SELLER

and

MERRILL LYNCH MORTGAGE INVESTORS, INC.,

PURCHASER

MORTGAGE LOAN SALE AND ASSIGNMENT AGREEMENT

Dated as of April 1, 2005

Terwin Mortgage Trust

(Asset-Backed Certificates, Series TMTS 2005-6HE)

TABLE OF CONTENTS

SCHEDULE

SCHEDULE A Mortgage Loan Schedule

This MORTGAGE LOAN SALE AND ASSIGNMENT AGREEMENT, dated as of April 1, 2005 (the “Agreement”), is executed by and between Terwin Advisors LLC (the “Seller”) and Merrill Lynch Mortgage Investors, Inc. (the “Depositor”).

All capitalized terms not defined herein shall have the same meanings assigned to such terms in that certain Pooling and Servicing Agreement (the “Pooling Agreement”), dated as of April 1, 2005, among the Depositor, the Seller, U.S. Bank National Association, as trustee (the “Trustee”), JPMorgan Chase Bank, N.A., as servicing administrator, securities administrator and backup servicer and Specialized Loan Servicing, LLC, as servicer (the “Servicer”).

WITNESSETH :

WHEREAS, pursuant to certain mortgage loan purchase agreements and the bring down letters related to such agreements (each, a “Transfer Agreement”), the Seller has purchased or received from various originators (each, a “Transferor”) certain mortgage loans identified on the Mortgage Loan Schedule attached hereto as Schedule A (the “Mortgage Loans”);

WHEREAS, the Seller desires to sell, without recourse, all of its rights, title and interest, other than the servicing rights, in the Mortgage Loans to the Depositor, to assign all of its rights and interest under each Transfer Agreement, and to delegate all of its obligations thereunder, to the Depositor; and

WHEREAS, the Seller and the Depositor acknowledge and agree that the Depositor will assign all of its rights and delegate all of its obligations hereunder to the Trustee, and that each reference herein to the Depositor is intended, unless otherwise specified, to mean the Depositor or the Trustee, as assignee, whichever is the owner of the Mortgage Loans from time to time.

NOW, THEREFORE, in consideration of the mutual agreements herein set forth, and for other good and valuable consideration, the receipt and adequacy of which are hereby acknowledged, the Seller and the Depositor agree as follows:

ARTICLE I

CONVEYANCE OF MORTGAGE LOANS

Section 1.01. Sale of Mortgage Loans . Concurrently with the execution and delivery of this Agreement, the Seller does hereby transfer, assign, set over, deposit with and otherwise convey to the Depositor, without recourse, subject to Sections 1.03 and 1.04, all the right, title and interest, other than the servicing rights, of the Seller in and to the Mortgage Loans identified on Schedule A hereto, having an aggregate principal balance as of the Cut-off Date of approximately $350,020,543. Such conveyance includes, without limitation, the right to all distributions of principal and interest received on or with respect to the Mortgage Loans on or after April 1, 2005 other than payments of principal and interest due on or before such date, and all such payments due after such date but received prior to such date and intended by the related mortgagors to be applied after such date, together with all of the Seller’s right, title and interest in and to each related account and all amounts from time to time credited to and the proceeds of such account, any REO Property and the proceeds thereof, the Seller’s rights under any Insurance Policies related to the Mortgage Loans, and the Seller’s security interest in any collateral pledged to secure the Mortgage Loans, including the Mortgaged Properties.

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Concurrently with the execution and delivery of this Agreement, the Seller hereby assigns to the Depositor all of its rights and interest under each Transfer Agreement, other than the Seller’s right to indemnification from the related Transferor for breaches of representations and warranties under such Transfer Agreement. Concurrently with the execution hereof, the Depositor tenders the purchase price of $337,248,874.11. The Depositor hereby accepts such assignment, and shall be entitled to exercise all such rights of the Seller under each Transfer Agreement, as if the Depositor had been a party to such agreement.

Notwithstanding the foregoing, if the Depositor pursues any remedy against the Seller pursuant to Section 1.04(b) and the Seller fully performs such remedy, and to the extent such remedy could also be enforced against the Transferor under the related Transfer Agreement, the Depositor shall be deemed to have reassigned such rights and remedies that the Depositor has against such Transferor back to the Seller but only to the extent necessary to permit the Seller to pursue such remedies against the related Transferor pursuant to the terms of the related Transfer Agreement and only with respect to the Mortgage Loan(s) as to which such remedy has been fully performed by the Seller.

Section 1.02. Delivery of Documents . In connection with such transfer and assignment of the Mortgage Loans hereunder, the Seller does hereby deliver, or cause to be delivered, to the Depositor (or its designee) the documents or instruments with respect to each Mortgage Loan (each a “Mortgage File”) so transferred and assigned, as specified in the applicable Transfer Agreement.

For Mortgage Loans (if any) that have been prepaid in full after the Cut-off Date and prior to the Closing Date, the Seller, in lieu of delivering the related Mortgage Files, herewith delivers to the Depositor an Officer’s Certificate which shall include a statement to the effect that all amounts received in connection with such prepayment that are required to be deposited in the account maintained by the applicable Servicer for such purpose have been so deposited.

Section 1.03. Review of Documentation . The Depositor, by execution and delivery hereof, acknowledges receipt of the Mortgage Files pertaining to the Mortgage Loans listed on the Mortgage Loan Schedule, subject to review thereof by the Custodian, on behalf of the Trustee, for the Mortgage Loans for the Depositor. The Custodian, on behalf of the Trustee, is required to review, within 45 days following the Closing Date, each applicable Mortgage File. If in the course of such review the Custodian, on behalf of the Trustee, identifies any Material Defect, the Seller shall be obligated to cure such defect or to repurchase the related Mortgage Loan from the Depositor (or, at the direction of and on behalf of the Depositor, from the Trust Fund), or to substitute a Replacement Mortgage Loan therefor, in each case to the same extent and in the same manner as the Depositor is obligated to the Trustee and the Trust Fund under the Pooling Agreement.

Section 1.04. Representations and Warranties of the Seller .

(a) The Seller hereby represents and warrants to the Depositor as of the date hereof that:

(1) The Seller is a Delaware limited liability company duly organized, validly existing and in good standing under the laws governing its creation and existence and has full power and authority to own its property, to carry on its business as presently conducted, and to enter into and perform its obligations under this Agreement;

(2) The execution and delivery by the Seller of this Agreement have been duly authorized by all necessary action on the part of the Seller; neither the execution and delivery of this Agreement, nor the consummation of the transactions herein contemplated, nor compliance with the provisions hereof, will conflict with or result in a breach of, or constitute a default under,

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any of the provisions of any law, governmental rule, regulation, judgment, decree or order binding on the Seller or its properties which conflict or breach would have a material adverse effect on the ability of the Seller to perform hereunder;

(3) The execution, delivery and performance by the Seller of this Agreement and the consummation of the transactions contemplated hereby do not require the consent or approval of, the giving of notice to, the registration with, or the taking of any other action in respect of, any state, federal or other governmental authority or agency, except such as has been obtained, given, effected or taken prior to the date hereof;

(4) This Agreement has been duly executed and delivered by the Seller and, assuming due authorization, execution and delivery by the Depositor, constitutes a valid and binding obligation of the Seller enforceable against it in accordance with its terms except as such enforceability may be subject to (A) applicable bankruptcy and insolvency laws and other similar laws affecting the enforcement of the rights of creditors generally and (B) general principles of equity regardless of whether such enforcement is considered in a proceeding in equity or at law; and

(5) There are no actions, suits or proceedings pending or, to the knowledge of the Seller, threatened or likely to be asserted against or affecting the Seller, before or by any court, administrative agency, arbitrator or governmental body (A) with respect to any of the transactions contemplated by this Agreement or (B) with respect to any other matter which in the judgment of the Seller will be determined adversely to the Seller and will if determined adversely to the Seller adversely affect its ability to perform its obligations under this Agreement.

(b) The representations and warranties of each Transferor with respect to the Mortgage Loans in the applicable Transfer Agreement were made as of the Closing Date. To the extent that any fact, condition or event with respect to a Mortgage Loan constitutes a breach of both (i) a representation or warranty of a Transferor under the applicable Transfer Agreement and (ii) a representation or warranty of the Seller under this Agreement, the Depositor shall have the right to enforce the obligations of the Seller and to the extent that the Seller fails to fulfill its contractual obligations hereunder then the Depositor shall have the right to enforce the obligations of such Transferor under any applicable representation or warranty made by it. If a Transferor fulfills its obligations under the provisions of the applicable Transfer Agreement by substituting for the affected Mortgage Loan a mortgage loan which is not a Replacement Mortgage Loan, the Seller shall, in exchange for such substitute mortgage loan, provide the Depositor (a) with the applicable Purchase Price for the affected Mortgage Loan or (b) within the two year period following the Closing Date, with a Replacement Mortgage Loan for such affected Mortgage Loan. Notwithstanding the foregoing, the Depositor will enforce the representations and warranties contained in Section 1.04(b) (8), (44), (45) and (47) only against the Seller and upon such enforcement any rights and remedies of the Depositor against the related Transferor regarding such representations and warranties will be considered to be reassigned by the Depositor back to the Seller. Subject to the foregoing, the Seller represents and warrants that as of the Closing Date, as to each Mortgage Loan, that:

(1) The information set forth in the Mortgage Loan Schedule is complete, true and correct in all material respects as of the Cut-off Date;

(2) With respect to a Mortgage Loan that is not a Co-op Loan, the Mortgage creates a first lien or a first priority ownership interest in an estate in fee simple in real property securing the related Mortgage Note. With respect to a Mortgage Loan that is a Co-op Loan, the Mortgage creates a first lien or a first priority ownership interest in the stock ownership and leasehold rights associated with the cooperative unit securing the related Mortgage Note;;

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(3) All payments due on or prior to the Cut-off Date for such Mortgage Loan have been made as of the Closing Date and the Mortgage Loan is not 31 days or more delinquent in payment and has not been dishonored, except that, as of the Cut-off Date, no more than approximately 2.00% of the Mortgage Loans may be between 31 days and 60 days delinquent (in each case, by aggregate Cut-off Date Principal Balance of all of the Mortgage Loans). The Seller has not advanced funds, or induced, solicited or to their actual knowledge, received any advance of funds from a party other than the owner of the related Mortgaged Property, directly or indirectly, for the payment of any amount required by the Mortgage Note or Mortgage;

(4) All taxes, governmental assessments, insurance premiums, water, sewer and municipal charges, leasehold payments or ground rents which previously became due and owing have been paid, or escrow funds have been established in an amount sufficient to pay for every such escrowed item which remains unpaid and which has been assessed but is not yet due and payable;

(5) The terms of the Mortgage Note and the Mortgage have not been impaired, waived, altered or modified in any respect, except by written instruments which have been recorded to the extent any such recordation is required by law, or, necessary to protect the interest of the Depositor. No instrument of waiver, alteration or modification has been executed. No Mortgagor has been released, in whole or in part, from the terms thereof except in connection with an assumption agreement and which assumption agreement is part of the Mortgage File and the terms of which are reflected in the Mortgage Loan Schedule;

(6) The Mortgage Note and the Mortgage are not subject to any right of rescission, set-off, counterclaim or defense, including, without limitation, the defense of usury, nor will the operation of any of the terms of the Mortgage Note or the Mortgage, or the exercise of any right thereunder, render the Mortgage Note or Mortgage unenforceable, in whole or in part, or subject to any right of rescission, set-off, counterclaim or defense, including the defense of usury, and no such right of rescission, set-off, counterclaim or defense has been asserted with respect thereto; and the Mortgagor was not a debtor in any state or federal bankruptcy or insolvency proceeding at the time the Mortgage Loan was originated;

(7) All buildings or other customarily insured improvements upon the Mortgaged Property are insured by an insurer acceptable under the Fannie Mae Guides, against loss by fire, hazards of extended coverage and such other hazards as are provided for in the Fannie Mae Guides or by Freddie Mac, as well as all additional requirements set forth in the Pooling Agreement. All such insurance policies contain a standard mortgagee clause naming the Seller, its successors and assigns as loss payee and all premiums thereon have been paid. All such standard hazard policies are in full force and effect. If required by the Flood Disaster Protection Act of 1973, as amended, the Mortgage Loan is covered by a flood insurance policy meeting the requirements of the current guidelines of the Federal Insurance Administration which policy conforms to Fannie Mae and Freddie Mac requirements, as well as all additional requirements set forth in the Pooling Agreement. Such policy was issued by an insurer acceptable under Fannie Mae or Freddie Mac guidelines. The Mortgage obligates the Mortgagor thereunder to maintain all such insurance at the Mortgagor’s cost and expense, and upon the Mortgagor’s failure to do so, authorizes the holder of the Mortgage to maintain such insurance at the Mortgagor’s cost and expense and to seek reimbursement therefor from the Mortgagor;

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(8) Any and all requirements of any federal, state or local law including, without limitation, usury, truth-in-lending, real estate settlement procedures, consumer credit protection, equal credit opportunity, disclosure and all applicable predatory and abusive lending laws applicable to the Mortgage Loan have been complied with in all material respects. To the best of the Seller’s knowledge, any and all statements or acknowledgments required to be made by the Mortgagor relating to such requirements which were in the Mortgage file when such Mortgage Loan was acquired by the Seller are and will remain in the Mortgage File;

(9) The Mortgage has not been satisfied, canceled or subordinated, in whole or in part, or rescinded, and the Mortgaged Property has not been released from the lien of the Mortgage, in whole or in part nor has any instrument been executed that would effect any such release, cancellation, subordination or rescission;

(10) The related Mortgage is a valid, subsisting, enforceable and perfected first lien on the Mortgaged Property, including for Mortgage Loans that are not Co-op Loans, all buildings on the Mortgaged Property and all installations and mechanical, electrical, plumbing, heating and air conditioning systems affixed to such buildings, and all additions, alterations and replacements made at any time with respect to the foregoing securing the Mortgage Note’s original principal balance. The Mortgage and Mortgage note do not contain any evidence of any security interest or other interest or right thereto. Such lien is free and clear of all adverse claims, liens and encumbrances having priority over the lien of the Mortgage, subject only to (1) the lien of non-delinquent current real property taxes and assessments not yet due and payable, (2) covenants, conditions and restrictions, rights of way, easements and other matters of the public record as of the date of recording which are acceptable to mortgage lending institutions generally and either (A) which are referred to or otherwise considered in the appraisal made for the originator of the Mortgage Loan, or (B) which do not adversely affect the appraised value of the Mortgaged Property as set forth in such appraisal, and (4) other matters to which like properties are commonly subject which do not materially interfere with the benefits of the security intended to be provided by the Mortgage or the use, enjoyment, value or marketability of the related Mortgaged Property. Any security agreement, chattel mortgage or equivalent document related to and delivered in connection with the Mortgage Loan establishes and creates a valid, subsisting, enforceable and perfected first lien and first priority security interest, in each case, on the property described therein, and the Seller has the full right to sell and assign the same to the Depositor;

(11) The Mortgage Note and the related Mortgage are original and genuine and each is the legal, valid and binding obligation of the maker thereof, enforceable in all respects in accordance with its terms subject to bankruptcy, insolvency, moratorium, reorganization and other laws of general application affecting the rights of creditors and by general equitable principles. All parties to the Mortgage Note and the Mortgage had the legal capacity to enter into the Mortgage Loan and to execute and deliver the Mortgage Note and the Mortgage. The Mortgage Note and the Mortgage have been duly and properly executed by such parties. To the best of the Seller’s knowledge, the Mortgagor is a natural person who is a party to the Mortgage Note and the Mortgage is in an individual capacity or family trust that is guaranteed by a natural person. No fraud, error, omission, misrepresentation, negligence or similar occurrence with respect to a Mortgage Loan has taken place on the part of Seller or the Mortgagor, or, on the part of any other party involved in the origination of the Mortgage Loan. The proceeds of the Mortgage Loan have been fully disbursed and there is no requirement for future advances thereunder, and any and all requirements as to completion of any on-site or off-site improvements and as to disbursements of any escrow funds therefor have been complied with. All costs, fees and expenses incurred in making or closing the Mortgage Loan and the recording of the Mortgage were paid or are in the process of being paid, and the Mortgagor is not entitled to any refund of any amounts paid or due under the Mortgage Note or Mortgage;

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(12) Immed