Authorities say they have arrested a Helena man who thought he was arranging a sexual encounter with a man and his 12-year-old son.

The Independent Record reported Tuesday the man found a police officer waiting for him instead.

Mark Steven Mlekush has been charged with attempted sexual intercourse without consent and attempted sexual abuse of children.

A Justice Court affidavit says a Helena police officer found the 48-year-old Mlekush online trying to meet a father and son.

Investigators posing as a father responded to the man. The affidavit says Mlekush described the sex acts he wanted to engage in and emailed pictures of his genitals.

The investigators arranged a meeting and arrested Mlekush when he showed up.

Mlekush was being held in Lewis and Clark County jail.