Police used a cellphone that belonged to a security guard found dead in the Denver Performing Arts Complex parking garage Friday morning to help track the man they believe stabbed him to death with a pocket knife.

The Denver coroner on Tuesday morning identified the guard as 39-year-old Scott Tice and ruled his death a homicide.

“An autopsy was completed and the cause of death was from sharp force injuries,” the Denver Office of the Medical Examiner said Tuesday.

Caleb “CJ” Schroeder, 23, was arrested Friday evening in Aurora for investigation of first-degree murder and robbery. Police found a bloody pocket knife in his pocket and a security badge pinned to his backpack, according to an arrest warrant affidavit.

An electrician found Tice’s body at 5:36 a.m. on the fourth floor of the performing arts complex garage on Curtis Street between 13th and 14th streets, according to Denver police. Tice, who worked for Allied Universal Security, was stabbed several times on the right side of his neck.

Tice left a trail of blood to the spot where he was found lying face up. His company-issued Samsung cell phone, equipped with tracking software that recorded Tice’s movements during his shift, was missing, but had been shut off after sending its last signal at 4:51 a.m.

Detectives reviewed Denver Police security camera footage and first saw the man later identified as Schroeder appearing on camera at 4:30 a.m. He was wearing a dark knit cap and was carrying a red fire extinguisher. When detectives traced his steps they found blood evidence along the way, the affidavit says.

At 4:49 a.m., security cameras captured the man leaving the parking garage Less than a minute later another camera captured the same person near 14th and Lawrence streets. By then he was not wearing a cap or carrying the fire extinguisher, the affidavit says.

At 5:53 p.m. Denver detectives tracked a ping from Tice’s cellular phone near East Colfax Avenue and Chambers Road in Aurora. A special bulletin was issued.

At 8:10 p.m. Aurora police Capt. Stephen Redfearn spotted a man at 13347 E. Montview Blvd. who resembled the picture on the bulletin, the affidavit says. When Redfearn got out of his car and approached the man he saw what appeared to be blood on his shirt.

When Redfearn asked the man if he had a weapon, the man said he had a knife. The captain arrested the man, Schroeder, who had a pocket knife that was covered in blood, the affidavit said.

Schroeder also had an Allied security badge pinned to the strap of his backpack.

Denver police later interviewed Schroeder at Denver police headquarters. A section of the report describing the interview was redacted.