A Utah man faces the probability of a death sentence after he was found guilty of killing 6 members of his extended family. A girl who survived the attack by playing dead testified against him.

Ronald Haskell, 39, murdered six members of the Stay family in July 2014; including 4 children. A Harris County Jury found him guilty of the killings on Thursday.

While prosecutors are pushing for the death penalty, it is up to the jurors to decide whether Haskell receives capital punishment or life in prison, NBC News reported.

Harris County District Attorney Kim Ogg said in a statement, "We are grateful for the jurors’ rapt attention over the last many weeks to every piece of evidence in the case."

According to police, Haskell traveled from California to Spring in Houston Suburb to ambush the family of his ex-wife’s sister including her husband and five children.

While four children of the Stay’s, Bryan (13), Emily (9), Rebecca (7), and Zach (4), were shot and killed, the fifth child, Cassidy (15) survived the attack after a bullet grazed her and she pretended to be dead.

The defense argued that Haskell was insane and heard voices, which made him commit the nefarious crime. However, according to the district attorney, Haskell had meticulously planned out the whole crime.

“There was never a reasonable doubt that Haskell meticulously planned and carried out the slaughter of the Stay family,” Ogg said in the statement.

Cassidy testified against Haskell at the trial, surrounded by her family. Before the guilty verdict was read, Cassidy prayed. Haskell hung his head, as the verdict came.

According to one of his defense attorneys Doug Durham, Haskell took the decision in the best way he could.

"He was aware that this was a strong possibility."

Neil Davis III, another Haskell defense attorney told KPRC that they would work to save his life.

“That’s our job,” Davis said.

This photo shows a view of the defendant's table in a courtroom closed due to budget cuts and layoffs, at the Stanley Mosk Courthouse in Los Angeles on March 16, 2009. Robyn Beck/AFP/Getty Images