The film crew of the upcoming Netflix original series “Mindhunter” came to Butler on Tuesday to analyze the exterior and interior of the Butler County Courthouse.

“They are apparently doing some filming here, and they asked for permission to use courtroom for part of their filming, and they were just here to see what it looked like,” said Tom Holman, deputy district court administrator.

About 25 crew members walked around with cameras, smart phones and tablets, taking photographs. They started across the street at Diamond Park before moving to the third floor of the courthouse, heading into a courtroom.

They analyzed walls, ceilings and hallways, comparing different angles and lighting.

The series is set in the 1970s. According to imdb.com, “Mindhunter” is about an agent in the FBI's Elite Serial Crime Unit tracking down serial killers and rapists.

“It's just proof positive that there's reasons to come to Butler,” said Butler Mayor Tom Donaldson. “It's a destination not just for people to come to dinner, but it's an interesting community, and our brightest days our still ahead of us.”

The lead will be Jonathan Groff, an actor who had roles in the Disney hit “Frozen” and the TV series “Glee.”

David Fincher, a producer of the series, also is slated to direct. Fincher has a directorial resume that includes "Seven," "Fight Club" and "Gone Girl." He also executive produces "House of Cards," the popular Netflix series staring Kevin Spacey.