ST PETER — Mike Lunderberg and his two sons sat in a pickup truck and watched Tuesday as a helicopter hovered over the St. Peter Regional Treatment Center Tuesday afternoon.

The noisy chopper and the occasional squad car cruising past on Highway 99, lights flashing, were the only clues Lunderberg needed to know someone had escaped from the facility.

At about 2 p.m., treatment center staff reported that 25-year-old William Daniel Pfeffer Jr. had left the facility. He was described as being white, 5’6” tall and 240 pounds with a black beard and shaved head. He is being treated in a lower security facility for people who are considered mentally ill and dangerous. Pfeffer was not in the Security Hospital or the facility for the Minnesota Sex Offender Program, which have higher security.

The search for Pfeffer was focused on the southeast corner of the treatment center’s large, wooded campus as Lunderberg sat at the end of his driveway off Highway 99, which is close to the opposite corner of the grounds.

“We’re supposed to have a warning system over here where someone calls a neighbor and that neighbor calls another neighbor,” he said. “We never get any of that. The only time we know something is going on is when the helicopter shows up and the sheriff’s cars start driving up and down the highway.”

Lunderberg said he wasn’t concerned. He has lived in St. Peter his entire life and has plenty of stories about past escapes. He talked about in incident in the 1970s when someone left the facility, swam across a swamp between the grounds and Highway 169 before walking into town. Wet and stinky, the man convinced Lunderberg’s father to let him use the phone.

A short time later the man was picked up by someone who met him at a nearby fast food restaurant.

“We didn’t even know what was going on until we watched TV that night and saw someone was missing,” he said. “Then my dad called the sheriff.”

Other squads, some from St. Peter and some from Nicollet County, were parked along Highway 169 Tuesday. Police officers and deputies were searching along the Minnesota River on one side highway and the around the rugged ravines on the other side. Several squads and a military-style vehicle were parked behind the barriers that block the old entrance off the highway.

In a house perched on a hill overlooking the new entrance that’s being built for the regional treatment center, Patrick Anderson said it was a message from a buddy on Facebook that let him now an escape had occurred.

Although Pfeffer has been committed with a history of assaults, Anderson said he wasn’t concerned. He has been living in the house, which is right next to the hospital grounds, for more than two years.

“When we bought the house, the insurance agent told us this is one of the safest houses in St. Peter because they want to get as far away as possible when they escape,” he said.

“I figure the first thing they’ll do is head for Mankato or go hop on a bus. But we still have a dog that barks when strangers are around.”