Yes, there was an interview with an interior designer named Katherine Shepard in the DM in which she said she had been invited to RH's house in 2005 to look over and measure the place in preparation for a kitchen reno. She saw the locked basement room and RH told her no one is permitted in there. He said because of the guns.
Interior designer Katherine Shepherd told DailyMail.com how Rex Heuermann did not allow her to enter a room in his basement at his Massapequa Park in 2005.
www.dailymail.co.uk
It's interesting because the first of the G4 wasn't killed until two years later. I wonder if that has implications for the possibility of earlier victims.