In what could potentially be the biggest bombshell to date in the Oscar Pistorius murder case, sources who are reportedly close to the investigation have alleged that the South African sprinter’s girlfriend, Reeva Steenkamp, is believed to have been pregnant at the time of her death.

According to the tabloid the National Enquirer, sources with knowledge of the situation say that Steenkamp likely told Pistorius she was expecting a child on the same day that she was fatally shot.

“Police believe the pregnancy secret she revealed is what sent Pistorius over the edge and left her dead, with bullet wounds to the head, chest, pelvis and hand,” a source described as an “insider” told the publication.

Before her untimely death in Pistorius’ home on Valentine’s Day, Steenkamp, a 29-year-old model and reality television personality, had been considered a rising celebrity in her native South Africa. According to the Guardian, the attractive couple formed, “South Africa 's equivalent of Posh and Becks."

Pistorius, who was granted bail by a South African magistrate on Friday, has argued that he did not intentionally murder Steenkamp, but shot her through a locked bathroom door after mistaking her for a burglar and then, realizing his mistake, unsuccessfully attempted to revive her with CPR.

The National Enquirer’s sources paint the Olympian in a rather different light, however, alleging that a “hot-headed” Pistorius was incensed over online communications Steenkamp had engaged in with her ex-boyfriend, Francois Hougaard.

“Police believe the argument started over Reeva’s relationship with Oscar’s close friend, handsome rugby player Francois Hougaard,” the source said. “Police believe as the arguing continued, hot-headed Pistorius became maniacal. Reeva tried to calm him down, saying there was nothing between Hougaard and herself. Although she had dated him in the past, it was long over.”

It was during the fight that sources for the publication alleged Steenkamp revealed that she was pregnant with Pistorius’ child; a claim he allegedly believed to be false, and which further enraged him.

The source also claimed that police currently believe that in that “rage,” “possibly induced by the illegal steroids that were later recovered in his home,” Pistorius used a cricket bat to bash Steenkamp’s skull in and also shot her.

The source also dismissed the defense’s claim that Pistorius mistook Steenkamp for a burglar, alleging that she had been at his home all day and that he was well aware she was there.

“That doesn’t make sense,” the insider told the tabloid. “Reeva had been in the house since 6 p.m. the day before – and he knew she was there. Police aren’t buying that story either and have charged him with premeditated murder.”