Ron Lee Haskell, 33, is said to have been on his way to kill his grandparents when the 15-year-old girl called 911 and told officers about his plans. They arrested him after a two-hour standoff in a suburban cul-de-sac in Spring, Texas.
Haskell’s victims were estate agent Stephen Stay, 39, and his wife Katie Stay, 34, and their four children – two boys, aged four and 14, and two girls, aged seven and nine.
Mrs Stay was the sister of Haskell’s estranged wife Melanie, who was out of Texas at the time of the massacre. It is believed they had separated and that they were about to divorce.
Police said he shot the Stays in the back of the head “execution style” after he had tied them up.
The teenage girl who survived, named by family friends as Cassidy, was in critical condition in hospital last night.
A magistrate’s court in Spring was told Haskell had tricked his way into the Stay household, which he approached wearing a FedEx delivery man’s uniform and asked Cassidy if her parents were home.
She said they were out, and he left only to return a little later. He again knocked on the door, was told her parents were not in, then asked her if she recognised him as her “ex-uncle”.
Cassidy tried to close the door but Haskell forced his way in and tied her up. When the rest of the family arrived home, he tied them up too and told them to lie face down on the floor and demanded they tell him where his estranged wife was.
When they said they did not know, he shot them all.
Cassidy survived because the bullet fractured but did not penetrate her skull. She is being treated at a hospital in Houston.
Thomas Gilliland, of the Harris County Sheriff’s Office, said from the information Cassidy had given them they were able to track the car Haskell was driving and corner him. There followed “two hours of constant talking with a man armed with a pistol to his head and who had just killed six people”.
Mr Gilliland described Haskell as “cool as a cucumber” and said when his officers first approached him, he was “just sitting in his car looking out at us”.
Haskell has been charged with murder and is being held at the Harris County jail.
Neighbours of the Stay family said they were Mormons, adding they were “very sweet and their kids were very shy”.