CHICAGO (AP) — Chicago’s police oversight agency said Friday it has closed an investigation after finding no wrongdoing by city officers followings allegations that they engaged in sexual misconduct with migrants housed at police stations.

The Civilian Office of Police Accountability said its investigators had not “substantiated any claim of sexual misconduct between members of the Chicago Police Department and any new arrivals.” COPA added in a statement that “to date no victim or witness has come forward or been identified.

The agency said the case “will be closed without allegations or findings of misconduct” but said it has the authority to reopen the investigation if it receives “new material evidence.”

Chicago is among the U.S. cities struggling to provide shelter and other help to hundreds arriving from the southern border, with families sleeping in police station lobbies. Migrants, largely from Central American countries, have been bused to Chicago and other major U.S. cities from Texas since the spring.

COPA opened its investigation in early July after a text message, circulated among police officers and other city employees, alleged that a 29-year-old field training officer assigned to the police department’s Ogden District had engaged in a sexual relationship with a 17-year-old female migrant who was housed at the police station, the Chicago Tribune reported.

Less than two weeks later, COPA’s chief administrator, Andrea Kersten, said at a news conference that the office had as of that time not located any victims or witnesses to corroborate any allegations.

Kersten added that COPA had also begun investigating a second allegation of a Chicago officer engaging in sexual misconduct with a migrant housed at the Town Hall District station on the city’s North Side.

After news of the investigation broke in July, Mayor Brandon Johnson said his administration remained “intensely focused on the deeply troubling allegations.”

The Associated Press left a message Friday with the mayor’s office seeking comment on COPA’s investigation finding no wrongdoing by officers.

Most of Chicago’s 14,000 migrants who have arrived seeking asylum since August 2022 have come from Texas, some under the direction of Republican Gov. Greg Abbott.

Hundreds of those migrants have found themselves seeking shelter in Chicago police stations as the city has struggled to find adequate housing for them, sometimes drawing the ire of local residents.

After the sexual misconduct allegations surfaced, city officials rushed to relocate migrants who were living at the Ogden District. The city then moved other migrants from the Town Hall District, but last month, as the migrant housing crisis continued to strain resources, asylum seekers were sent back to those stations, the Chicago Sun-Times reported.