A Santa Rosa father made a citizen’s arrest and provided police detectives with Snapchat messages that led to the arrest of a Clearlake man last week on suspicion of sexually assaulting an 11-year-old girl, Santa Rosa police said Tuesday.

Francisco Aparcicio Cortes, who police said is in his 20s, allegedly exchanged hundreds of Snapchat messages with the girl, some of which were sexual in nature, Sgt. Terry Anderson said, and there is evidence the two had a physical relationship.

The father initially called police Dec. 21 to report a man shining a flashlight into his daughter’s room at their Santa Rosa home, Anderson said.

The suspect, who claims to be from Clearlake but has recently lived in Santa Rosa, was allegedly seen driving in the neighborhood without his headlights when police arrived around 2:30 a.m., Anderson said.

The misdemeanor crime was not seen by the responding officers so they were unable to press charges, Anderson said. But the father made a citizen’s arrest, and Aparcicio Cortes was taken to the Sonoma County Jail where he was booked for misdemeanor peeping and held on $1,000 bail.

His vehicle was also towed.

The following day, Dec. 22, the father went to police to show detectives messages he found on a Snapchat account his daughter had created on a family member’s cellphone, Anderson said.

A week later, Dec. 29, Aparcicio Cortes went to the Santa Rosa Police Department to retrieve his vehicle, at which point detectives were called in. He was arrested on suspicion of sexually assaulting a minor and booked in Sonoma County Jail on $1 million bail.

You can reach Staff Writer Nick Rahaim at 707-521-5203 or nick.rahaim@pressdemocrat.com. On Twitter @nrahaim.