A part-time police officer in Pennsylvania was arrested on Thursday after he was caught taking inappropriate photos and videos of children at a YMCA late last month, according to the Chester County District Attorney's Office.

Authorities said Mark Mackrell, 52, who worked as a part-time officer for the Millbourne Borough Police Department in Delaware County, was charged with photographing a sexual act, stalking, unlawful contact with minors and related offenses, following an incident on July 22.

According to the Chester County DA's Office, police were notified of a "suspicious condition" at the YMCA on Airport Road in East Goshen Township the day after the incident, July 23. A mother told police that her 14-year-old daughter and her 13-year-old friend believed they were being filmed while they played at the YMCA pool on July 22.

According to the affidavit of probable cause, the mother approached the man suspected of taking pictures of the kids. However, the man denied taking any pictures or videos, refused to identify himself and refused to show his phone. The mother then reported the incident to the YMCA lifeguards, who approached the suspect and asked for identification. 

The lifeguard said the suspect refused to identify himself and instead showed his police badge.

Authorities identified the suspect as Mackrell, of Coatesville, and then later searched his phone, where they found photos and videos of children, some dating back as far as July 2024.

Investigators said the videos appeared to be taken by Mackrell, who can be heard making sexual comments about the juveniles in multiple videos.

Mackrell was arrested on Thursday and later released after posting $100,000 bail. According to the affidavit, Mackrell also serves as a youth monitor at Abraxas Academy, a multi-service facility offering secure residential treatment and detention services in Morgantown, Pennsylvania.  

Millbourne Borough Police Department said in a statement that Mackrell is suspended while the charges are pending.

"The Millbourne Borough Police Department stresses that it has zero tolerance for any behavior jeopardizing the safety of children and will continue to zealously investigate any such misconduct and take appropriate action to ensure the safety of the residents of Millbourne Borough and the surrounding communities," the statement says in part. 

If anyone has information about Mackrell or the incident, they're asked to call Westtown-East Goshen Police Department at (610)-692-9600.