BOZEMAN, Mont. (AP) — A former Bozeman man charged with trying to get nude photos from someone he believed was a 16-year-old girl argues the police sting that led to his arrest violated his expectation of privacy on his Facebook account and the charge should be dismissed.

William Harris Windham IV has pleaded not guilty to felony attempted sexual abuse, The Bozeman Daily Chronicle reported.  Windham, 28, was arrested in May 2013 after going to meet the person he thought was the girl in front of a Bozeman store. The teen was actually an undercover detective.

Public defender Annie DeWolf argues a detective was conducting an online pornography investigation, to which Windham was not the subject, when the online conversations took place.

She said Windham sets his Facebook privacy settings at the highest level and there is no evidence that he requested or accepted a friend request from the girl under the profile name of Tammy Andrews.

“It is sinister indeed when the government can without a warrant enter into a personal space without consent,” DeWolf argued in her Sept. 23 motion.

Charging documents allege the conversation began in April 2013 when Windham asked Tammy Andrews how they knew each other. She identified herself as a 16-year-old girl from Bozeman, and they exchanged photos. Windham then sent her a nude photo of himself and asked for one of her, which she declined, the documents said.

He also expressed an interest in having sex with Tammy.

A few weeks later, Windham messaged that he wanted to see Tammy naked, and she said she wanted to meet first, setting up his arrest.

Deputy Gallatin County Attorney Eric Kitzmiller argued Windham’s statements about his desire to have sex with the girl were admissible.

Investigators said Windham consented to a search of his computer and cellphone.

The state argues Windham could have no expectation of a privacy right for his Facebook messages or his texts because an electronic record was created that the other party could have shared them with someone else.

DeWolf has until Oct. 21 to respond to the state’s brief.