SAXONBURG — A couple married for 25 years died of carbon monoxide poisoning in an apparent double suicide this weekend at their house in the borough, authorities said.

Earl J. Reith, 67, and his wife, Melinda Reith, 56, were found in an antique truck about 2:30 p.m. Saturday, said Saxonburg police Chief Joe Beachem.

The truck was in a detached garage at their home on North Rebecca Street. The couple was side by side in the front seat.

Investigators believe the couple Friday night or early Saturday morning turned on the truck’s engine with the garage door closed, and stayed there until they died.

Butler County Deputy Coroner Chuck Lewis pronounced the Reiths dead at the scene of suicidal asphyxiation by carbon monoxide. Autopsies were not conducted, but results of routine toxicology tests are pending.

“All the evidence that we’ve gathered would indicate it’s a double suicide,” said Beachem, who added the investigation continues.

He said the couple left behind a handwritten note.

“The note made clear what their intentions were,” Beachem said. “But it gave no clues as to why.”

A family member, concerned that no one had heard from the couple in two days, found the bodies.