Father kills 12-year-old foster daughter to protect his own teenage son who got her pregnant

The Thorburn family 
By: Feng Qian

(Scroll down for video) Four members of one family in Australia, were arrested over the murder of their foster daughter.

Prosecutors said that the foster father killed the 12-year-old girl last year, after his son confessed to having sex with her and he was afraid that he impregnated the girl.

The foster father, Rick Thorburn, 56, was charged with murder and his 19-year-old son, Trent Thorburn, who had sex with the girl at least two times, was charged with incest.

Trent allegedly told his cousin on social media that he had sex with his foster sister after she threatened to kill his dog.

Trent sent the message to his cousin via Facebook Messenger, where he admitted to having sex with Tiahleigh Palmer shortly before her disappearance and he said that he was worried that he got her pregnant, according to police.

Palmer's body was found on a riverbank in Beenleigh, Queensland.

Police arrested Rick Thorburn after it was confirmed that he was the former owner of a 2009 Ford XR6 sedan that was seized by police last week in relation to the investigation.

The foster father was charged with murder and interfering with a corpse.

The 19-year-old foster brother was charged with two counts of perjury and incest.

Foster mother Julene, 54, and her 20-year-old son Joshua, were each charged with attempting to pervert the course of justice and perjury.

An attorney for the 19-year-old son asked the judge to grant him bail as he does not have a criminal history. However, the judge denied the request.

His father is in a medically induced coma at a hospital after he collapsed in jail following his arrest.