Almost certainly, Metro has that kind of arrangement. It's common, if a transit agency doesn't want to set up a whole separate police force like BART.

SacRT contracts for officers from the police departments of the cities it runs in, plus the sheriff, on specific assignment to transit policing. There have been a lot more actually on the trains recently as they spiff up their image for service to the new arena; we'll see how long that lasts. I'm sure the fare collectors are happy for the backup, as the "private security" previously used pretty much ignored whatever was going on, unless they were actively part of it.