According to Sheriff Dennis Richards, James J. Henke, 46, of Pardeeville, is suspected of stabbing and killing Thomas G. Kratz, 43, of Montello.
Deputies found Kratz in the street, near the curb, with a single stab wound from a large straight-bladed knife, according to Columbia County Sheriff's Department Detective Lt. Roger Brandner.
Kratz may have been stabbed during an argument with Henke about a woman both were involved with, Brander said.
Kratz, who was taken to Divine Savior Healthcare in Portage, was pronounced dead about 6 a.m. Tuesday.
Henke was taken into custody at the scene and was cooperative with authorities.
About 1:50 a.m., the Sheriff's Department received a 911 emergency call about an incident on North Main Street.
Brandner said officers found Kratz in the street near the curb, and he had a stab wound.
Brandner did not say where Kratz was stabbed. Kratz was pronounced dead about 6 a.m. on Tuesday.
Henke was taken into custody at the scene and was cooperative with authorities.
"He did not flee," Brandner said. "He was there when we arrived."
Deputies executed a search warrant mid-morning at 128 N. Main St., where Henke lives in a second-story apartment across the street from the stabbing. Richards said the knife used was found on the roof of the building.
Brandner said District Attorney Jane Kohlwey would determine if any charges will be filed.