A former campaign aide to Mayor Vincent C. Gray is scheduled to be sentenced in July after he admitted making illegal campaign contributions and destroying records.

Thomas W. Gore, who served as the campaign’s assistant treasurer, pleaded guilty last year to providing illegal donations to a minor mayoral candidate in the 2010 Democratic primary and to destroying a notebook that documented the payoffs. Gray eventually defeated incumbent mayor Adrian M. Fenty.

Gore, one of three former Gray campaign aides to plead guilty to a federal crime, has been cooperating with the government’s broader investigation.

He could face 12 to 18 months in prison, although prosecutors could recommend a lesser sentence.

Assistant U.S. Attorney Ellen Chubin Epstein agreed to Gore’s request to set a sentencing date of July 26. But she cautioned that the government was not making any promises about whether to seek a lesser sentence because of Gore’s cooperation.

“This should not be interpreted one way or another,” Epstein told U.S. District Judge Colleen Kollar-Kotelly.