Vaughn was arrested at the scene, Assistant District Attorney David W. Rahauser said Wednesday.
Trooper Jeremy Matas testified at Vaughn's Jan. 30 preliminary hearing that Vaughn told him the two had argued over Caldwell wanting him to move out of the house and about her seeing another man.
In another case, a man charged with attempted murder for a Jan. 8 shooting in Chambersburg was scheduled for the May trial term after pleading innocent.
Lucas Ismond, 39, of 141 Greenmeadow Lane, Chambersburg, is also charged with aggravated assault, a firearms violation and recklessly endangering others, according to court records.
Chambersburg police said the shooting at 61 W. South St. was called in at 7:41 p.m. When police arrived at the house, they found Roy Morris, 27, of Shippensburg, Pa., on the kitchen floor.
Ismond arrived at the house a short time later and collapsed on the sidewalk, according to testimony from Detective Diane Kelso at Ismond's Feb. 6 preliminary hearing.
According to police, Morris and Ismond were arguing and were told to leave the house by the tenant, Herman "Tippy" Parker. Both returned, resumed the argument and fired shots at each other, police said. Both men were taken to Hershey Medical Center following the shooting.
Morris was never charged in the incident. He was released from the hospital on Jan. 14, and Pennsylvania State Police said he shot himself Feb. 1 at a self-storage business in Fayetteville.
Since his release from the hospital, Ismond has been in Franklin County Prison on $500,000 bond.