LA PORTE COUNTY, Ind. (WLS) -- A former Michigan City police officer was arrested Tuesday in the alleged sexual assault of a woman with diminished mental capabilities, the La Porte County Sheriff's Office said.Thomas K. Jackson, who resigned from the Michigan City Police Department on March 14, was taken into custody without incident around 7:35 a.m. at a convenience store near Trail Creek, Ind., where he lives.The 51-year-old's arrest on four counts of rape was the result of an investigation carried out by sheriff's detectives at the request of the Michigan City police chief."He always seemed like a good guy, but he was always very flirtatious. We knew something wasn't quite right, but we never imagined he could do something like this," said Shelly Yanke, the suspect's acquaintance.Jackson allegedly had inappropriate contact with a La Porte County woman's adult daughter, who police were told has "such diminished mental capabilities that she could not have consented to such activity."Shortly after the arrest, word spread quickly through town on social media."From what I read on Facebook, it was like he was in a relationship with someone who wasn't mentally capable of consenting. I don't know, you can't really trust anyone nowadays," resident Frank Taffe said.The former officer was taken to the La Porte County Jail, where he was held in lieu of a $25,000 cash-only bond.