SALEM – A mentally challenged person who apparently torched a group home in Lynn on Lewis Street in 2008 because he was reportedly drinking, causing approximately $50,000 in damage, is considered a danger but remains free on his own personal promise to return to court with specific restrictions.Donald G. Armstrong, 42, who currently is in residence at Bridgewell, a group home located at 11 Paradise Road in Swampscott, entered his plea of innocent Friday morning in Salem Superior Court to a charge of arson of a dwelling house, in connection with the Nov. 10, 2008 blaze that torched an unoccupied home at 28-30 Lewis St. in Lynn.As jointly recommended by the prosecutor and defense, Judge Timothy Q. Feeley agreed to let Armstrong remain free pending his trial with the following conditions.Feeley agreed to find that Armstrong still remains a danger to the community, but that there are conditions of release which would insure the safety of the public which include that he remain at the group home, comply with all the program’s rules at the facility and can’t leave the facility unless escorted by a staff member.In addition, Armstrong is to not possess any matches or lighters, remain alcohol and drug free and report weekly in person to probation until his case is resolved.Police believe the blaze started in a storage area of the basement at 28-30 Lewis St. and that Armstrong used a lighter to start the fire, which reportedly caused approximately $50,000 in damage, according to Assistant District Attorney Christina P. Ronan.Defense attorney William Martin told Feeley that “drugs had nothing to do with the crime; allegedly beer had something to do with it.”The case was continued to Sept. 16 for a pre-trial conference.