PITTSBURGH (KDKA) – A man was arrested after he allegedly followed a woman on the riverfront trail, held a knife to her neck and indecently assaulted her.

The police report the victim said she was walking along the riverfront trail near Station Square when Robert Williamson ran up behind her an held a knife to her neck.

The victim told police he continued to walk behind her, making threats and inappropriately touching her.

(Photo Credit: Allegheny County)

He then allegedly threw her to the ground and assaulted her.

The victim said he put the knife down after she begged him to, at which point she said she threw the knife, punched Williamson in the back of the head and broke free.

Police say they recovered a knife from the scene. They also say surveillance footage allowed them to identify Williamson.

According to police, Williamson was previously charged and convicted of criminal attempted homicide, criminal attempted rape and other charges.

He was also charged with, but found not guilty, of failure to register as a sex offender.

They say Williamson will be transported to the Allegheny County Jail and charged with several charges, including aggravated assault, terroristic threats and indecent assault.

The victim was transported to Mercy hospital by medics for her injuries.