Angelo Correia, 24, was arrested Friday. Investigators said they received an anonymous tip that helped them identify Correia as the suspect and determine where he lived.
The stabbing happened Jan. 13 at the station located on Vermont Avenue and Santa Monica Boulevard. Metro spokesperson Jose Ubaldo said the male passenger was traveling to Union Station when he was stabbed in the throat. He was taken to the hospital, where he was pronounced dead.
"As the train was approaching the stop, the suspect reportedly approached the victim and stabbed him one time before he fled the train in the train station," said L.A. County Sheriff's Dep. Kim Manatt.
The victim was later identified as Jose Velasco-Alvarado, 34, of Los Angeles.
The motive for the fatal stabbing remains unknown. It remains unknown if the incident was a random act of violence or an isolated incident.
Correia was booked for murder at the West Hollywood Station and is being held on $1 million bail.