CASPER — The man arrested on suspicion of shooting a woman at a central Casper home early Tuesday is her adult son, police said Wednesday.

Larimer County, Colorado, sheriff’s deputies detained Andrew Steplock, 27, of Casper, at about 11 p.m. Tuesday, Casper Police Chief Keith McPheeters said at a press conference. Wednesday morning, authorities served Steplock with an arrest warrant for second-degree murder.

In addition, Steplock is being held in Colorado on allegations of aggravated burglary and possession of a firearm with unlawful purpose. Authorities have begun the process of extraditing him to Wyoming.

McPheeters said he did not know if Steplock had a lawyer.

Steplock’s mother, 58-year-old Deborah Steplock, “received a critical wound that is not survivable,” McPheeters said during remarks made at the Casper Events Center. She was being kept alive to honor her wishes to donate her organs, the chief said.

“While immediate family members still journey back to Casper, we ask that they be given privacy during this difficult time,” police said in the statement.

Police continue to investigate a motive in the crime, McPheeters said. Investigators do not currently believe Andrew Steplock had any accomplices, but McPheeters noted police continue to investigate the case. When asked about weapons, the chief said police are still in the process of serving warrants in the area.

McPheeters said Steplock has spoken with Casper police detectives but he declined to characterize the contents of the interview. The chief said he could not yet address specific circumstances of the crime.

Casper police arrested Steplock last week on suspicion of marijuana possession. An arrest affidavit filed in the marijuana case indicates he told police he was living in a building that property records show is owned by the railroad. McPheeters did not think that crime is related to the murder case.

Court records indicate Steplock has never before been charged with a felony in Wyoming.

Officers found Deborah Steplock at a home just south of downtown at about 1 a.m. Tuesday while responding to a security alarm. Her husband was performing first aid on her when police arrived, McPheeters said. She was taken to Wyoming Medical Center in critical condition.

Police believe Andrew Steplock left Casper shortly after the shooting.

There is no continuing threat to the public, the chief said. He thanked Casper officers for working 36 hours without sleep and thanked more than a dozen agencies, including the FBI and the Secret Service, for assisting with the investigation.