Washington — The internal watchdog for the government agency that manages federal properties is launching an investigation into the process behind the selection of a site in Maryland for the FBI's new headquarters, according to a letter released Thursday. 

For years, the General Services Administration and FBI were considering three locations in Virginia and Maryland to replace the crumbling headquarters in downtown Washington, D.C. Lawmakers from both states lobbied heavily to bring the new building to their respective locations.

Earlier this month, the GSA announced that it had selected Greenbelt, Maryland, as the bureau's new home. The pick prompted an unusual public spat between the head of the agency and FBI Director Christopher Wray, who expressed concerns about the culmination of the yearslong process to select the site. 

"I had hoped this message would include our enthusiastic support for the way GSA arrived at its selection," Wray wrote in an email to FBI employees reviewed by CBS News at the time. "Unfortunately, we have concerns about fairness and transparency in the process and GSA's failure to adhere to its own site selection plan."

The selection of the Maryland site also drew pushback from Virginia lawmakers. Democratic Sen. Mark Warner wrote to acting Inspector General Robert Erickson two weeks ago expressing his concerns about the process.

Responding to Warner on Thursday, Erickson wrote that the GSA's Office of the Inspector General is "initiating an evaluation of GSA's selection of the site," with the objective being "to assess the agency's process and procedures for the site selection to relocate the FBI Headquarters."

"We intend to begin this work immediately and will share with you and the relevant committees a copy of any report which may result from this evaluation," Erickson wrote.

The fight over the new FBI headquarters

Wray — who was tapped to lead the FBI in 2017 — wrote in his message to bureau employees that he was concerned about "a potential conflict of interest involving the site selection authority and whether changes [the individual in charge] made in the final stage of the process adhered to the site selection criteria." The bureau's concerns about the process, he added, remained "unresolved."

GSA Administrator Robin Carnahan shot back in a public statement of her own, accusing Wray of making "inaccurate claims directed at our agency, our employees, and our site selection plans and process."

"Any suggestion that there was inappropriate interference is unfounded. The choice of Greenbelt, Maryland, is fully consistent with the decision-making process as well as all laws, regulations, and ethical considerations," Carnahan's statement said. "We stand behind the process, the decision, and all of the public servants who carefully followed the process and made a good decision on behalf of the FBI and the public."

During congressional testimony earlier this month, Carnahan revealed that the GSA's legal counsel reviewed Wray's concerns and found them to be without merit. 

Members of Virginia's congressional delegation welcomed news of the inspector general's probe in a statement on Thursday.

"Given the overwhelming evidence suggesting that the [GSA] administered a site selection process fouled by politics, we agree that an inspector general investigation is the appropriate next step. We applaud the inspector general for moving quickly and encourage him to move forward to complete a careful and thorough review. In the meantime, the GSA must pause all activities related to the relocation until the IG's investigation is complete," said the group of lawmakers, including Warner and Democratic Sen. Tim Kaine.

Following the public dustup between Wray and the GSA administrator, Maryland Democratic Rep. Steny Hoyer, who had been a vocal advocate for the Greenbelt location, said he was "disappointed" by Wray's stance and hoped that he would comply with GSA's decision. He pushed back against any insinuation that the decision was political, arguing Greenbelt is less expensive and closer to the Metro than the proposed Virginia site, making transportation for employees more convenient.

The FBI did not immediately respond to CBS News' request for comment on the new inspector general's investigation. A GSA spokesperson said the agency "continues to welcome a review of our decision-making process for the FBI headquarters site selection" and stands by the decision.