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from www.tmz.com – Hugh Hefner’s son Marston Hefner has officially been charged with roughing up his Playmate girlfriend … and now faces over a year in jail — this according to the Pasadena City Attorney.

TMZ broke the story … Marston was arrested earlier this month after allegedly attacking Playmate of the Year Claire Sinclair inside the couple’s Pasadena apartment.

A rep for the Pasadena City Attorney’s office tells us, Marston was charged yesterday with one count of inflicting corporal injury on a spouse or cohabitant.

We’re told Marston has also been charged with vandalism — after he allegedly damaged Claire’s lap top during the heated argument.

If convicted on both counts, Marston faces a year-and-a-half behind bars.