Johnny Thomas case is puzzling

Milwaukee County Supervisor Johnny Thomas, charged by the DA with taking a $500 bribe, has suspended his campaign for Milwaukee city comptroller. 

DA John Chisholm says he's confident the charge will stick; Thomas's lawyer says he's innocent. 

What's puzzling is that Thomas was arrested in mid-December but charges were just filed.  He knew they were coming; why did he proceed to file for office, raise money, collect endorsements, etc? 

He was an impressive candidate.  If he was trying to leverage his committee chairmanship on the County Board to squeeze contributions from bidders and contractors, it's a sad end to a promising politician.  

Here's the complaint.