Charges have been refiled against a Vancouver man accused of assisting convicted murderer Matthew Starr in covering up the February 2012 shooting death of their roommate near Vancouver Lake.Zachary J. Mattson, 21, of Vancouver appeared Thursday in Clark County Superior Court on suspicion of first-degree rendering criminal assistance, tampering with physical evidence, making false or misleading statements to a public servant and obstructing a law enforcement officer. Judge David Gregerson held Mattson in lieu of $30,000 bail and appointed Vancouver attorney Shon Bogar to defend him. He is scheduled to be arraigned on the charges June 5.Starr, 21, admitted in November to fatally shooting his roommate, Joshua R. Schenk, 25, after they went target shooting on Lower River Road near Vancouver Lake with Starr’s two friends, Mattson and Zackery Searcy, on Feb. 29, 2012. Starr apparently wanted Schenk dead so that he could take his valuables, according to court records.Starr initially told investigators that one of the shooting party’s rifles accidentally discharged, striking Schenk, and Starr then shot Schenk in the back of the head to put him out of his misery, court records say. In November, however, he pleaded guilty to the first-degree premeditated murder. He was sentenced to 23 years in prison.Mattson helped Starr drag Schenk’s body to a resting place about 4 or 5 feet away from the shooting location and cover it with a plastic tarp, according to court papers. He allegedly also misled investigators about what happened on the day of the murder. Joshua Schenk, who was killed in 2012, holds his niece, Mirra, in 2009.