Sheriffs hunting the violent intruders who broke into Australian dad Brenton Estorffe's Texas home and shot him dead have released a surveillance photo of a possible getaway car.
An emotional Fort Bend County Sheriff Troy Nehls also gave descriptions on Friday of the two men who smashed a glass window just after midnight on Wednesday at the rear of Mr Estorffe's home in the quiet neighbourhood of Katy, near Houston.
Sheriff Nehls and his investigative team are desperate to capture those behind an attack that left Mr Estorffe's wife Angeleanna a widow and their one-year-old and three-year-old children without a dad, shocking the community.
"They are going to pay for this," Sheriff Nehls told reporters at a press conference.
"They came into the wrong community."
The sheriff said there have been seven homicides in the county this year and six were solved.
A photo of a light-coloured four-door sedan with what is believed to be a sunroof was captured on a residential surveillance camera just before the shooting, and shown leaving just after shots were fired.
Further analysis is under way to determine the car's make and model.
Sheriff Nehls described one intruder as possibly being "dark-skinned", five foot and 11 inches tall (180cm), of medium build and wearing a dark-coloured hoodie.
The second intruder had dark-coloured skin, was six foot tall (182cm), of a slim build and had a buzz haircut.
A $US25,000 ($A36,500) reward has been offered for information leading to the men's capture.
Sheriff Nehls also raised the possibility of a third accomplice, possibly a getaway driver, or more offenders at the home.
Why the intruders targeted the Estorffes remains a mystery, and investigators are considering if it was a case of mistaken identity.
The family's cars were in the driveway and the house had exterior Halloween decorations.
"Anybody would know there is obviously children in that house," the sheriff said.
"There's Halloween decorations.
"You could almost make the safe assumption these individuals knew someone was at home but they still had the audacity to break a window and enter the home.
"That's a little unusual folks."
The Estorffes only moved into the house six months ago and investigators are looking into who lived there previously to determine if the intruders mistakenly targeted the wrong people.
Sheriff Nehls said it appears the intruders made a hole in a fence to gain access to the rear of the house and in the darkness smashed a window to gain access.
Mr Estorffe confronted the men and was shot.
Sheriff Nehls praised the father's bravery.
"He gave his life in defence of his family," the sheriff said.
"What more honour can you bestow on an individual than that."
A GoFundMe page has been set up to raise money for Mr Estorffe's widow and children.
Estorffe, 29, was formerly from Mooloolaba on Queensland's Sunshine Coast.
He moved to the US in 2011 to play American football and study at South Virginia University.
He had been working for the Enterprise car rental company in Texas.
Sheriff Nehls said his detectives are emotionally motivated to solve the crime.
"You have young detectives that have family of their own walk into a residence and see the pictures on the walls of a young father, pictures of his children," he said.
"You can see the love he has for his family.
"That can bother us a bit."