The boyfriend of "Amish Mafia" star Esther Schmucker is locked up in a Pennsylvania prison for allegedly using the reality star's face as a punching bag ... and then trying to shut her up.
Imir R. Williams was captured by a police task force in Lancaster, PA this morning ... he'd been hiding out since Sunday when cops named him the suspect in Esther's beating -- which left her with a broken nose and cheekbone.
Schmucker reportedly went to a hospital for treatment after last Thursday's attack -- accompanied by Williams. Her roommate told police Williams was "guarding her" to make sure she didn't rat him out.
But cops say Schmucker did eventually come forward 3 days later to tell them about the alleged attack.
Williams is being held in the Lancaster County Prison on $250,000 bail.