Authorities say a serial rapist who remains on the loose after attacking more than a dozen women in two Kansas college towns has been tied to another case.

Police in Riley County and Lawrence announced during a joint news conference Thursday that a July 2015 attempted rape in Manhattan is the latest case linked to the unidentified suspect. The man also is suspected in 12 other rapes and one other attempted rape from 2000 to 2008.

Authorities are urging other women who may have been victimized to come forward. Police say all but one of the attacks occurred during school breaks at Kansas State and the University of Kansas. Officials have said the suspect is usually armed.

A $10,000 reward is being offered for information that leads to an arrest.