The Granville, N.Y., man charged with fatally shooting his father — a Pawlet Selectboard member — and two other relatives had shown signs of serious mental illness and other concerning behavior that had scared some family members, according to police. Brian Crossman Jr., 22, faces three charges of aggravated murder. He is accused of killing Brian Crossman Sr., stepmother Erica (Pawlusiak) Crossman, and her 13-year-old son, Colin Taft, at their home in Pawlet in the early morning hours of Sunday, September 15. A police affidavit filed in Vermont Superior Court in Rutland describes a grisly scene at the Crossmans’ farmhouse on Route 133. The younger Crossman was staying with the family for the weekend when he took several shotguns from a gun cabinet and shot each family member multiple times. Investigators found the mother and teenage child in their respective bedrooms, while Crossman Sr.’s body appeared to have been dragged into a mudroom. The elder Crossman, who worked for Green Mountain Power, left the home for a late-night service call and returned home just before 1 a.m. Around 3:30 a.m., the younger Crossman began placing phone calls to 911 and family members, according to a police review of phone records. The alleged killer met with a Vermont State Police corporal outside an elementary school around 4 a.m. His shirt and pants were covered in blood. He told police that he had gone for a long walk and discovered all three family members dead upon his return. He said he tried to use a vehicle to take his father’s body across the street to his grandmother’s house before changing his mind. Blood patterns inside the home, coupled with the placement of Crossman Jr.’s clothes and headphones, contradicted his story, police wrote. Surviving family members in Vermont and New York State told investigators that the younger Crossman had acted in unusual and unsettling ways for years. His biological mother told investigators that her son had sought inpatient psychiatric treatment at times but was not currently taking any medications. His behavior had escalated two years earlier, she said, when he began talking to himself and experiencing wide swings in his mental stability, according to the affidavit. Family members reported that Crossman Jr. had a strained relationship with his father and at one point told a family friend that he would kill him one day, the family friend told police. Crossman Jr…