Janesville police guard the scene of a double shooting the morning of May 21 on the city's south side.

JANESVILLE—The Rock County Medical Examiner’s Department has released the names of the men involved in what police have called a murder-suicide in Janesville on May 20.

The men are Carlos A. Cruz Portillo, 27, of Janesville, and Phong Thao, 43, of Madison.

Janesville police have said they believe the shooter in the incident was a 43-year-old Madison man.

Cruz Portillo and Thao were both pronounced dead at the scene, and autopsies confirmed they died from “firearm-related trauma,” according to a news release from the medical examiner.

The medical examiner’s office is conducting “additional testing,” according to the Friday news release.

Investigators believe Thao was involved in a domestic relationship with a Madison woman, and the two had a child together. The woman and the two men all worked at B&G Foods in Stoughton.

Thao suspected that Cruz Portillo and the woman were together, went to the Town and Country Mobile Home Park, 1105 Kellogg Ave., on the night of May 20.

Police believe Thao shot Cruz Portillo “multiple times” and then shot himself with a handgun in the presence of the woman, said Janesville police Lt. Chad Pearson.