LAGUNA NIGUEL ( — A man was arrested Monday on suspicion of killing another man in his Laguna Niguel apartment.

Steven Richard Gilbert, 59, of Laguna Niguel, was arrested in connection with the homicide of Thomas Robert Marston, 53, also of Laguna Niguel. Marston sustained what appeared to be a stab wound, but authorities said the coroner’s office will determine his cause of death.

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Deputies were called to a home in the 29000 block of Palo Drive on the report of an unconscious man found inside the home who was unresponsive. Gilbert was identified as a possible suspect, but was not at the home, Orange County sheriff’s officials said.

Investigators did not say why Gilbert was immediately identified as a possible suspect.

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Marston was taken to Mission Hospital, where he was pronounced dead.

Gilbert was later found driving in Mission Viejo, where he was detained without incident. He has since been arrested for murder and booked on $1 million bail.

His first court appearance was scheduled for Tuesday.

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Anyone with information about the crime can call the Orange County Sheriff’s Department at (714) 647-7000 or (714) 647-7044.