BUTLER TWP — A 20-month-old boy suffered a fractured skull, a broken rib and numerous bruises and other injuries at the hands of his father at the family's apartment on Colleen Street, authorities said.

Butler Township police last week charged Jerald L. Lorenz, 37, with felony assault in the incident, which left the child hospitalized in Pittsburgh.

Lorenz has been in the Butler County Prison since Feb. 12 on an unrelated domestic relations warrant and a probation detainer. He is to be arraigned Thursday on a list of charges for allegedly abusing his son between Nov. 22 and Dec. 6, 2018.

Police began their investigation Dec. 7 when they received a ChildLine report from UPMC Children's Hospital of Pittsburgh, according to court documents.

The toddler was taken to the hospital Dec. 6 where an examination found he had a “parietal skull fracture and bruising to the head, neck and shoulders,” documents said.

Additional injuries were found on the child's face, ears, mouth, tongue, arms, abdomen and genitals.

The injuries caused the boy “substantial pain and impairment of function,” according to the hospital's findings.

Medical staff forwarded the report of suspected child abuse to the Children's Advocacy Center.

The report noted that if the toddler was “returned to the same environment in which he sustained these injuries, he is at risk for further injuries and even death.”

At the time, the child was living with Lorenz and his mother, the defendant's girlfriend of about five years, police said. The couple are the biological parents of another child, a 2-year-old girl, who also was living with them along with the woman's other child, a 10-year-old.

The mother told investigators that she first noticed the toddler had bruises “in unusual places” Nov. 23, documents said.

She described the injuries as “penile bruising and left hip bruising.” She did not seek medical attention.

Police Detective Justin Weldon later interviewed the woman, who recalled feeding the child from a bottle Dec. 5. The child vomited and she gave him a bath.

She did not see any injuries on the child when she left him with the defendant to go to work that night.

When she returned the next morning, police said, she found the child in bed with Lorenz, where she had left her son.

She saw the bruises on the child and said, “Oh my God, where did this come from?” according to Weldon's affidavit.

Lorenz didn't know, she told investigators.

Police noted that the bed's box spring and mattress were laying on the carpeted floor. The bed, they said, was not high enough “to cause those injuries from simply falling off.”

The mother and the defendant took the boy and their daughter to day care at the YMCA in Butler on Dec. 6.

Less than an hour later, she got a telephone call from the YMCA staff inquiring about the boy's bruises. YMCA officials also notified the county's Children and Youth Services.

A CYS caseworker advised the mother to take the boy to Children's Hospital, where the child was diagnosed with a skull fracture, bruising and other injuries.

“There was no accidental trauma history provided that would reasonably explain the multitude of injuries in this toddler,” documents said.

Two other police detectives formally interviewed Lorenz on Jan. 4. He “repeatedly stated he did not know how the victim was injured,” police said.

He said he first noticed a bruise on his son's head the morning of Dec. 6. He suggested the boy “could've rolled down the steps,” documents said, possibly in early December.

Detectives asked him about “intentionally causing the injuries to the victim.”

The defendant admitted he “smacked” the boy “a few times, but not hard,” police said.

He recounted he hit the boy for pulling the 2-year-old's hair and pushing her over, documents said. He allegedly claimed he last slapped the toddler Dec. 3 or 4.

Lorenz said he “went to slap the victim's hand,” according to the affidavit, “and the victim moved it causing (Lorenz) to slap the victim in the face.”

The defendant also allegedly recalled that when the boy dirtied his diaper in November, he may have been “a little rough” cleaning up the child around his genitals.

Police did not believe Lorenz's account of how the boy was injured.

“It is reasonable and probable that (he) intentionally struck and/or caused physical contact with the victim,” documents said, “and caused substantial pain and injury” to the child.

Lorenz is charged with two counts of aggravated assault of a child and one count of child endangerment, all felonies. He also is charged with a misdemeanor count of simple assault and a summary count of harassment.

Police said Tuesday that the boy remains with his mother and siblings, and they believe the child is “doing fine and is going to make a full recovery.”