St. Paul police are investigating an apparent homicide after a 33-year-old man was found dead inside his home Monday evening.

A friend called 911 to report an assault after discovering the man in the city’s W. Seventh neighborhood shortly before 5 p.m., authorities said. Paramedics found Matthew R. Schramm unresponsive and pronounced him dead at the scene.

At a news conference Tuesday afternoon, police spokesman Steve Linders said autopsy results led detectives to believe the death is a homicide, but he declined to elaborate on what possible trauma the victim had. Police won’t say whether the man was shot or whether weapons were found at the scene.

A formal cause of death is pending from the Ramsey County Medical Examiner’s Office.

The 911 caller was questioned by police and later arrested on outstanding warrants unrelated to the homicide investigation. No arrests have been made in the case.

Authorities have visited the house on the 1700 block of Benson Avenue more than 30 times in the past seven months — mostly on calls of suspicious activity, suspicious vehicles, drug possession and disturbances. Schramm has co-owned the small rambler since 2016, according to county property records.

Some friends and relatives were clearing Schramm’s house out late Tuesday afternoon but declined to comment, saying they didn’t know what happened.

“We’re all shocked by this,” a neighbor and longtime friend of the family said. “This is a quiet neighborhood.”

Anyone with information is asked to call the St. Paul Police Department’s homicide unit at 651-266-5650.