EVERETT — Everett police have arrested a man for investigation of assaulting his girlfriend’s 2-year-old son.

It was the second arrest Monday involving alleged child abuse. The man was booked into the county jail late last night for investigation of first-degree assault of a child.

Police believe he is responsible for breaking a toddler’s leg Sept. 12. The broken femur and multiple bruises were discovered by medical staff at The Everett Clinic, Everett police Sgt. Robert Goetz said. The boy was taken to Children’s Hospital and Regional Medical Center in Seattle, where doctors told investigators the boy’s injuries likely were the result of child abuse, Goetz said.

Initially the man told police that the boy had fallen but later said he grabbed the boy’s leg, Goetz said.

He is expected to appear in Everett District Court today.

The babysitter of another injured toddler also is expected to go before a judge today. The man, 31, was arrested Monday morning for investigation of assaulting a 1-year-old boy he was babysitting on Sept. 13. That boy suffered a broken jaw, and fractures to an arm and his ribs. He also has a severe head injury and is in an assisted living facility.

The man told police that the boy fell down some stairs. Doctors believe the boy’s injuries aren’t the result of an accidental fall, according to police.