D.C. Attorney General Irvin B. Nathan and council member Jim Graham have agreed to allow a council investigation into Harry Thomas Jr.’s theft of more than $300,000 from the city to continue, but only if it does not interfere with ongoing criminal and civil probes.

The agreement, a copy of which was obtained by The Washington Post, was signed late Monday afternoon after Nathan and Graham, who is chairman of the Human Services Committee, agreed that the council probe of the nonprofit Children and Youth Investment Trust Corp. would be limited.

“There will be no public activity including the issuance of subpoenas without prior consultation” with the attorney general, the letter states.

On Friday, Graham (D-Ward 1) released an extensive report that alleged some of the trust’s officials may have been negligent or too complacent in their monitoring of a 2007 earmark requested by Thomas. The former Ward 5 council member stole about $350,000 after the trust forwarded the money to two nonprofit groups — Langston21 Century and SwingAway LLC — that prosecutors allege were under his control.

But Graham said he won’t be able to finalize his report until his committee receives subpoena authority to compel more witnesses to testify. On Friday afternoon, the Human Services Committee voted to authorize subpoena authority, but Nathan and Mayor Vincent C. Gray (D) questioned the need for another investigation.

In a letter sent to council members Monday afternoon, Nathan expressed concern that Graham’s probe could conflict with those underway by his office, the U.S. Attorney’s Office and the D.C. Auditor.

Nathan noted that his office has launched a broad review “of the District’s funds, with particular emphasis on a number of nonprofits, why they were selected, and what they did with money that remains unaccounted.”

He stressed it may be inappropriate for council members to look into a matter that could also touch their own offices as the probe intensifies.

“In light of the revelations involving the diversion of Trust funds by then-Councilmember Thomas, Jr., and questions that have been raised about the role of some members of the Council and staff relating to funding of the Trust over the years, we respectfully request that no committee of the Council should conduct its own investigation into the Trust at this time,” Nathan wrote.

A few hours later, after conversations between Graham and Nathan and D.C. Council Chairman Kwame R. Brown (D), Nathan scaled back his opposition to a separate council investigation.

In a joint letter signed by Nathan and Graham, the two men agreed that the council probe would not stray from Thomas’s interaction with the trust, as well as the reasons why Ellen London, the former executive director of the trust, was fired last month.

Graham would also have to consult with Nathan before issuing any subpoenas, and promised “a swift completion” of the council investigation, the letter states.

Thomas, who faces up to four years in prison, is scheduled to be sentenced Thursday. The full council must vote before Graham can receive the authority to compel witness testimony.