The IRS has provided information on how a victim of tax related identity theft may obtain a copy of the return filed by the other party at https://www.irs.gov/Individuals/Instructions-for-Requesting-Copy-of-Fraudulent-Returns.

A taxpayer looking to obtain a copy of the fraudulent return is required to send a letter containing the following information to the IRS:

Taxpayer’s name
Taxpayer’s identification number
Tax year(s) of the fraudulent return(s) being requested
The statement “I declare that I am the taxpayer” with the taxpayer’s signature underneath
A copy of a government-issued identification (driver’s license or passport)

The letter must be sent to:

IRS
P.O. Box 9039
Andover, MA 01810-0939

The taxpayer’s authorized representative or another individual may also obtain this information. In that case the information to be submitted includes:

Requestor’s name and identification number
Relationship to the individual (authorized representative, parent, etc.)
Mailing address of the requestor
CAF number if one has been assigned for the authorization
Tax year(s) of the fraudulent return(s) being requested
Taxpayer’s name
Taxpayer’s identification number
Taxpayer’s mailing address
The following statement, with the requestor’s signature beneath: “I declare that I am a person authorized to obtain the tax information requested.”
A copy of a government-issued identification (driver’s license or passport)
A copy of documents demonstrating the individual’s right to receive the data (Form 2848, court order, etc.) unless
The request is for information of a minor child being made by the parent of the minor child or
The authority to receive information is on file with the IRS and the requestor’s CAF number is being provided

The return will have some information redacted. The IRS provides the following reason why data will be redacted:

The IRS may disclose return information from a fraudulent return to a person whose name and SSN are listed as the primary or secondary taxpayer when the disclosure does not seriously impair Federal tax administration. Although some information will be redacted or partially redacted, the remaining information will allow you to determine what information the identity thief may have about you and your family.

The current year and the previous six years may be requested. The returns that can be requested are Forms 1040, 1040A, 1040EZ, 1040NR, or 1040NR-EZ.

The IRS provides information on how long it will take to get a copy of the return as follows:

The time required to fulfill your request will depend on a number of factors. One factor is whether there are any open, unresolved issues with a tax return for a tax year requested. These are very complex cases, and we will need to resolve the underlying identity theft case before we can provide the return. The IRS will acknowledge your request within 30 days of receipt and within 90 days you will receive the return or follow-up correspondence.