MARENGO TOWNSHIP, Mich. (WOOD) — A man who was missing after going for a walk on Sunday was found by a drone that was searching for heat signatures.

Around 10 p.m., deputies with the Calhoun County Sheriff’s Office were sent to Michigan Avenue near Partello Road after receiving a report about a missing person.

The caller said her husband, a 73-year-old man, had left home around 4 p.m. to take a walk on the property and hadn’t returned.

When deputies arrived, K-9s and the drone team were called to assist. The sheriff’s office said due to weather, a helicopter was not an option.

The drone team found a heat signature over the waist-deep swap area, southwest of the home. Deputies said the man was partially submerged in the water.

At the time, temperatures were in the mid to upper 20s, the sheriff’s office said.

Fire crews carried him over 100 yards on a backboard to the main road where additional medical personnel was waiting. He was then taken to the hospital where he died.

Deputies were treated for extended exposure to freezing water temperatures, the sheriff’s office said.

The incident remains under investigation.