BUTLER TWP— The mother of 4-year-old Bentley Thomas Miller is the latest defendant to be charged in connection with her son's slaying.

Butler Township police today arrested MacKenzie Paige Peters, 21, of Butler with two felony counts of child endangerment. She was arraigned and later released on $25,000 unsecured bail.

Investigators allege Peters “failed to seek appropriate medical treatment” for a “severe burn” Bentley suffered to the top of his hand and wrist while in the care her boyfriend, Keith Jordan Lambing.

Police said Lambing, 20, was baby sitting the boy at the Super 8 hotel in Butler Township on March 21 when he sexually assaulted the child. The alleged assault caused Bentley to bleed to death, according to the court documents. He also had numerous other injuries, authorities aid.

Lambing is charged with homicide, rape of a child and numerous other charges in the death. He is being held in the Butler County Prison without bail.

Lambing and Peters had been staying at the Super 8 for four to six days when the boy died. While searching the couple's room, police found “evidence of drugs and/or drug paraphernalia,” documents said.

Also at the motel with the couple was Peters' 4-month-old son, police said.

Investigators described Bentley's burn as “being significant enough that any reasonable caretaker would have sought medical treatment for wound care and pain management,” documents said.

Lambing called his own mother, Kristen Lee Herold,43, of Butler on the morning of March 21 and asked her to pick up the child, according to police. While Herold was driving Bentley to his father's home in Butler, the boy became unresponsive. She pulled over at a Butler shopping plaza and called 911.

Paramedics said when they got there, the boy he was “bleeding excessively.”

Bentley was pronounced dead at Butler Memorial Hospital less than an hour later, police said.

Herold was arrested last week and she is charged with child endangerment, reckless endangerment and hindering apprehension. She is in the county prison on $200,000 bail.