RCMP investigators search for evidence at the location where Const. Heidi Stevenson was killed along the highway in Shubenacadie, N.S. on Thursday, April 23, 2020. Court documents released today describe the violence a Nova Scotia mass killer inflicted on his father years before his rampage, as well as the gunman's growing paranoia before the outburst of shootings and killings.THE CANADIAN PRESS/Andrew Vaughan