Janesville police say they were alerted to 87-year-old Robert Patterson's apparent life of illicit sex activity after the man reported being robbed at gunpoint. Patterson called police in April after the armed robbery, and police began investigating the case.

When they canvassed the neighborhood around the area of Patterson's storage facility on Delavan Drive, they found multiple people offering information about things that went on inside the storage facility.

Police investigators eventually found a trunk inside Patterson's storage area which contained decade's-worth of pictures of naked women and meticulous notes detailing sexual favors he received from many women over the years. Police say the items in the trunk date back to the 1940s.

Patterson was arrested this week after months of investigation.

He is expected to be charged with soliciting prostitution and maintaining a place for prostitution.

His arrest comes at a time when Janesville police are making a concerted effort to crack down on online sex trafficking.