The third and final suspect in the fatal stabbing of a 25-year-old man on a Metro A Blue Line train in Long Beach was behind bars on June 20.

Gael Cruz-Gonzalez, 21, was arrested Sunday at Los Angeles International Airport, where U.S. Customs and Border Patrol agents stopped him as he was attempting to fly to Mexico, according to the Long Beach Police Department.

Long Beach police took custody of Cruz-Gonzalez and booked him into the Long Beach City Jail, where he was being held on $2 million bail, police said.

He is suspected in the April 12 death of Luis Fernando Polita, of Los Angeles. He was found aboard a Metro train in the 100 block of East First Street with multiple stab wounds to the upper body. He was taken to a hospital, where he later died.

Investigators determined that Polita boarded the train in an undisclosed area outside of Long Beach. At some point after the train entered Long Beach, the suspects boarded the train, immediately approached the victim, and physically assaulted him, police said.

During the attack, one of the suspects pulled out a knife and stabbed the victim multiple times, police said. When the train came to a stop at the Metro station near First Street and Pine Avenue, the suspects exited and fled on foot prior to officers’ arrival, police said.

Police said at the time a motive for the attack was unclear, but subsequently said it appears the assault was “the result of a dispute that originated on the Metro Rail.”

Two other suspects—Akili Collins, 18, and Melake Daniel, 19, both of Long Beach—were arrested two days after the attack in the 900 block of East Broadway in Long Beach.

Collins was subsequently charged with murder, while Daniel was charged with murder and assault by means of force likely to cause great bodily injury. Daniel has already pleaded not guilty to the charges. Collins is due in court for arraignment on June 21.

Collins is being held without bail, according to jail records. Daniel is being held on $2 million bail.

Anyone with additional information about the fatal stabbing was urged to contact homicide Detectives Donald Collier or Chasen Contreras at 562-570-7244. Tipsters who choose to remain anonymous can contact Crime Stoppers at 800-222-8477.