The killing, police said, was "particularly disturbing."
Authorities believe the suspect killed his wife and dismembered her body in an abandoned Pasadena restaurant, placing her remains in a suitcase that he then carried aboard a Metro Gold Line train.
Five stops later, he hopped off in Cypress Park and rode his bicycle — the suitcase still in tow — to the parking lot of a Home Depot. There, police say, the man lit the grisly package on fire.
On Tuesday, prosecutors charged the suspect, Valentino Gutierrez, a 56-year-old homeless man, with murder and arson. The Los Angeles Police Department tentatively named the victim as Tiana Alfred, 31, but said her body was so badly damaged that coroner's officials had not yet confirmed her identity.
"To dismember an individual like that is pretty grotesque," LAPD Capt. Billy Hayes told reporters Tuesday afternoon. "It takes an awful lot of effort and determination by an individual, which is pretty cold."
The investigation began shortly after 1:30 a.m. Thursday, when firefighters doused the fire, LAPD officials said. Once it was out, Chief Charlie Beck said, they opened the suitcase and found "dismembered body parts" inside.
Detectives from the LAPD's Robbery-Homicide Division, which handles high-profile or particularly complex investigations, immediately took the case. Investigators soon found surveillance footage showing a man riding a train with the same suitcase, Beck said.
Other people were on the train at the time — shortly after midnight on Thursday — but it didn't appear that they interacted with Gutierrez, Hayes said. What was odd about the suitcase, the captain added, was that it appeared heavy.
"There was nothing that we can see that was out of the ordinary," Hayes said.
After watching the footage, detectives determined Gutierrez got on the train at the Fillmore Station in Pasadena, Hayes said. There, they used a police bloodhound to follow his trail.
Investigators interviewed homeless people in the area who helped identify Gutierrez as the suspect, police said.
"Their statements also tied him to the murder," Beck said.
Police arrested Gutierrez shortly after 10 a.m. Friday after he left a homeless shelter in Pasadena, authorities said. They also identified the scene where they believe he dismembered his victim, the shuttered Dona Rosa Bakery and Taqueria at California Boulevard and Arroyo Parkway. Pasadena police said its officers had responded to the location three times last year for "homeless-related concerns."
Hayes said detectives found forensic evidence there but declined to elaborate. They are still searching for the murder weapon, he said, as well as a motive.
Police believe Gutierrez killed Alfred sometime on Jan. 30, Hayes said. The couple had been living at a Pasadena homeless shelter for several months, he added.
Gutierrez had a lengthy criminal history, LAPD Deputy Chief Justin Eisenberg said, including convictions for robbery, battery, domestic violence, drugs and possession of a deadly weapon.
If convicted of the arson and murder charges, prosecutors said, he faces up to life in prison.
6:55 p.m.: This article was updated with additional information about the suspect and his movements and comments from police.
2:45 p.m. This article was updated with information about charges filed by prosecutors.
11:45 a.m.: This article was updated with additional information about the suspect and the nature of the crime.