Authorities in Wood County are after a man they're saying is behind several sexual assault charges.

David Hopp, 59, from the town of Saratoga, was last seen in December at the Germantown home of his estranged wife. The charges were all filed in May, stemming from three separate incidents.

Authorities are saying the first happened in October 2003 at his Saratoga home. The criminal complaint is saying he used straps and ropes to tie his then-girlfriend to a metal pole in his basement, then assaulted her.

In December 2005, court papers are saying he followed a woman around Wisconsin Rapids. He's also accused of assaulting another woman the next day in the same fashion as the first incident.

Police are saying they traced calls from that Germantown home to the third woman's place, offering her money to forget everything. They think Hopp may have left the area.

If you know anything, call the Wood County Sheriff's Department at (715) 421-8700.