The 17-year-old girl accused of playing a role in the murder of her grandparents has now also been formally charged in the case.

Cassandra Bjorge and her 19-year-old boyfriend Johnny Rider have been charged with murder and aggravated assault in the deaths of Randall and Wendy Bjorge, both 63 years old.

Police said the cause of death for both victims was an incision to the throat. Both victims also suffered blunt force trauma and sharp force injuries.

Investigators said they believe the couple was dead about a week prior to being found on April 8.

Police said they had initially responded to the residence on April 6 for an attempted welfare check at the request of relatives. At the time, there was no obvious reason to enter the residence. On April 8, when the victims' car was recovered from a different location, it was determined that force should be used to enter the home.

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According to investigators, they have reason to believe that after the murders, teens other than Bjorge and Rider may have been inside the home. Police said the other teens were not related to the actual deaths, but may have information proving critical to the ongoing investigation.

Police said they are asking parents in the area to talk to their teens to see if they were in the house or had contact with the suspects between April 1 and April 8. If so, investigators would like to speak with them.

Gwinnett Police said that between October 2015 and March 2017 they responded to the victims' Lawrenceville home 31 times for various reasons -- 18 of those times on runaway calls. Several of those calls were domestic dispute calls and illegal drug suspicion calls.

11Alive News had previously not released the girl’s name because she hadn't yet been charged with a crime and was in the hospital after what police believe was a suicide attempt. That all changed Wednesday night after police confirmed she was facing murder charges.

Rider, who was also hospitalized, had already been booked into jail on separate charges related to an earlier incident in which he allegedly beat his sister with a baseball bat and pepper sprayed her.

According to police records, this is not Cassandra Bjorge's first run-in with violent behavior. When she was 16-years-old, she was charged with assaulting her grandmother. Police had also been called to the residence several times in the past after the teen ran away.

Police called this a "very unique and disturbing case on so many levels," and said they may not ever find a scenario that makes sense to a "reasonable person."