A Joliet man who pushed his way into a bedroom and slashed his sister and her boyfriend with a knife while the couple was having sex was arrested early Tuesday morning, Joliet police said.

Clarence E. Knight III, 20, of 410 Bellarmine, faces a felony charge of aggravated battery for punching his 23-year-old sister in the head, cutting her left hand and slicing the right side of the 37-year-old boyfriend's nose, leaving a 1-inch wound, Cmdr. Al Roechner said.

The three had been together at a home at 823 Cardinal Lane when the sister and her boyfriend decided to go to an upstairs bedroom, Roechner said. When Knight realized where they were, he grabbed a knife, charged into the room and attacked the couple, he said.

The boyfriend was transported to Silver Cross Hospital in New Lenox. The sister did not require medical treatment, Roechner said.

Although only 20, Knight has already been arrested twice previously on felony charges -- once in January 2010 for armed robbery and again in June 2011 for robbery.

In addition to the aggravated battery charge in this case, Knight was also arrested for a parole violation, Will County jail records show.

Knight's being held in the county jail; his bond hearing is set for 1:30 p.m. Wednesday.

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