Surrey Police has referred itself the the Independent Police Complaints Commission, while it investigates the deaths of two women in Farnham.
There have been reports guns were confiscated from the property seven months before the two were found with gunshot wounds. The weapons were later returned.
A spokesperson for the Independent Police Complaints Commission confirmed the matter had been referred to them. They said: "We have a referral and are assessing it to determine our level of involvement."