What happen if you stab someone?

ok so two friends of mine are currently in jail. they got setup by this girl. she knew they were going to stab a guy. the guy came and someone was recording it but not the stabbing. they were just recording my friends back. the guy ended up getting stabbed in the face.he is ok. they gave the video to the police and my friends were arrested within 2 weeks one after the other. the guy recovered in the hospital and went to mexico. if he does not testify will they get out?