Suspected Indiana serial killer Darren Deon Vann told authorities he liked to revisit his victims’ dead bodies in the abandoned homes after he killed them, according to Sheriff Tom Dart of Cook County in Illinois.

In an interview Thursday, Dart compared the investigation into Vann to the investigation into serial killer John Wayne Gacy saying, "When you’re dealing with someone who kills a lot of people, give up trying to predict."

Vann, 43, has been charged with two homicides and is suspected in at least four others after leading police on a bloody scavenger hunt in Northwest Indiana. All of the victims were believed to be sex workers, officials said.

Police said Vann has hinted that his crimes stretch back 20 years.

"The thing that is so tragic about this ... these are just these women that have these horrific lives and now it’s ending in this," said Dart.

Illinois law enforcement officials said Vann may have been in Chicago's south suburbs between the time the first body was found and when he was arrested. The officials spoke on the condition of anonymity because they weren't authorized to discuss the investigation into Darren Vann.

Investigators were using Vann's cellphone records to pinpoint his movements after he told police he liked to check on the status of bodies he'd previously stashed after a fresh kill, authorities said.

Investigators were searching 16 abandoned buildings in Illinois on Wednesday and Thursday as part of the investigation into Vann's movements after the body of 19-year-old Afrikka Hardy was found, authorities said.

"Trying to predict was he being accurate when he said he killed loads of people? Don’t know," Dart said. "Could he have just killed a few? Don’t know. It’s all going to play itself out. From a law enforcement standpoint, whether you’re here in Cook County or you’re in Indiana or Texas for that matter, if you’re not going at least to his areas where his patterns were with abandoned buildings, people involved in the prostitution trade, you’re really making a horrible mistake.”

A judge ordered Vann be held in contempt of court Wednesday when the former Marine refused to even acknowledge his name during an initial court hearing in Hardy's slaying.