Other murderous gang members?
The Hillarites would have had to pay off the MS-13 shot=callers for them to use "disposable" assassins and then get rid of them. Not outside the realm of possibilities.
Bagster
Lesser Oracle
After all, even the dumbest MS-13 guy can see where the Joses and Guillermos of the gang end up dead doing 'special' jobs for the bosses.