CBS) – A Gary, Ind. man has been arrested in connection with a series of robberies and home invasions targeting seniors in Hammond and Lansing, a crime spree that included the sexual assault of an 81-year-old woman.

Lansing police say David Washington, 34, was arrested Friday as part of a joint investigation with Hammond police. Seniors in both Lansing and nearby Hammond have been the victims of a series of robberies and attacks dating back to Oct. 5.

Widely reported was an Oct. 15 home invasion in which an 81-year-old woman was forced into her Lansing home, sexually assaulted and robbed. This incident followed the Oct. 12 battery and robbery of a 79-year-old man at his Lansing home.

Police put together a composite drawing of the suspect, and a connection became apparent between incidents in Lansing and Hammond, authorities say.

Leads directed police to Washington, who "gave a voluntary statement about his involvement in the incidents" to Hammond police, a news release issued Monday said.

Police say they found several firearms in a vehicle associated with Washington, a convicted felon.

He is held in the Lake County, Ind. Jail, where he is facing multiple charges for the Hammond robberies; charges are pending in the Lansing incidents.

Washington is a non-compliant sex offender in the State of Illinois, authorities say.