Thomas Ryan Williams, 21, was charged with 18 counts of second-degree felony child abuse in January after doctors at Primary Children's Medical Center questioned the origin of multiple fractures found while examining his baby.

Williams pleaded guilty in August to three counts of second-degree felony child abuse as part of a plea deal where prosecutors dismissed the other 15 counts.

In addition to serving prison time, Judge Sheila McCleve ordered Williams to pay $12,540 in restitution.

Investigators believe the newborn was abused several times starting between around Nov. 22 and Dec. 29, according to charging documents.

The documents state Williams told Salt Lake County sheriff's investigators that he cared for the infant while the baby's mother was at work.

He told police he got "frustrated" when the baby cried and said he had "been rough" with the child, charging documents state. He told police he thought he broke the girl's arm and ribs and possibly injured her by bending her legs too far back while changing her diapers.

Hospital doctors who examined the baby Dec. 29 discovered multiple rib fractures, dislocated elbows, multiple leg fractures and a broken collarbone.

They notified authorities, who arrested Williams and the child's mother, 21-year-old Lupe Perez.

Perez - who was not charged in Utah - was extradited to Las Vegas, Nev., where she and Williams both are under investigation for killing a 2-month-old child in 2006, according to the Salt Lake County Sheriff's Office.

The injured 5-week-old girl was taken into state custody, along with her 1-year-old sister, who was also suffering from a bone fracture.

mrogers@sltrib.com