LOS ANGELES (CBSLA) – A 30-year-old Utah man appeared in court facing multiple charges in a Los Angeles-area crime spree in which he is accused of slaying two men, including an off-duty L.A. County Sheriff’s deputy, and committing two robberies.

Rhett Nelson. (LASD)

Rhett McKenzie Nelson faces two counts each of murder in the killings of 50-year-old Deputy Joe Solano and 30-year-old Dmitry Koltsov. He did not enter a plea during his initial Thursday arraignment.

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Investigators believe the killings were random in nature.

Nelson also faces one count of attempted murder and two counts of second-degree robbery, the L.A. County District Attorney’s Office reported Thursday. He faces special circumstance allegations of multiple murders and murder by means of discharging a firearm from a motor vehicle. The killings were committed with a handgun, prosecutors say.

San Diego police say Nelson may also be a suspect in five armed robberies and attempted armed robberies that took place from June 7-9 in that area.

Deputy Joe Solano in an undated photo (LASD)

Koltsov was killed at 4:50 p.m. Monday in a drive-by shooting while standing outside a building in the 1900 block of East 7th Place in downtown L.A. He was pronounced dead at the scene, according to the sheriff’s department.

Solano, off-duty and in civilian clothes, was ordering food shortly before 6 p.m. Monday at a Jack in the Box at 2531 W Valley Blvd. in Alhambra when a man walked up behind him brandishing a handgun and shot him in the back of the head, according to the sheriff’s department. The suspect fled in an SUV.

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Solano, a 13-year LASD veteran, was hospitalized on life support before passing away Wednesday.

Authorities believe that after killing Solano, Nelson committed two armed robberies in Long Beach. One happened at a Shell gas station and the second at a 7-Eleven.

Surveillance photos of the suspect and his SUV. (LASD)

Nelson, who is described as a runaway, called his father from a church in Long Beach and said he shot two people, investigators told CBS2. Nelson may be suffering from schizophrenic tendencies, sources said. His father told detectives Nelson has battled drug addiction.

On Tuesday morning, Long Beach police in the 2400 block of Granada Avenue spotted a Kia Sorrento SUV which matched the description of the getaway vehicle used by the suspect in Solano’s killing. Officers detained the driver, identified as Nelson. A gun was also recovered which matched a description of that used to kill Solano, the sheriff’s department said.

The DA’s office said it has not yet decided whether to seek the death penalty against Nelson if he is convicted. Otherwise, he would face a maximum sentence of life in prison without parole.

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Nelson’s father, a prominent Utah doctor, hired a private attorney for his son. Nelson is being held without bail and is due back in court July 22 for further arraignment.