A Georgia teen and her boyfriend horrifically murdered her grandparents and may have invited people over, police say

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New details emerged Thursday in the brutal slaying of a Gwinnett County couple allegedly killed by their 17-year-old granddaughter and her 19-year-old boyfriend.

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Wendy and Randall Bjorge, 63, were found dead about 11 p.m. Saturday in their home in the 1900 block of Furlong Run near Lawrenceville, Gwinnett police said.

“According to the medical examiner,” police Cpl. Deon Washington 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.”

Cassandra Bjorge and boyfriend Johnny Rider allegedly stabbed, punched, kicked and used a tire iron on the girl’s grandparents, according to warrants obtained by Channel 2 Action News.

Bjorge’s mother, Amanda Sterling, told Channel 2 she “needs everybody’s love and support and strength” as she processes the charges against her daughter in her parents’ deaths.

And that’s not all police revealed Thursday.

Investigators now believe the couple had been dead about one week before authorities found them and other teens “unrelated to the actual homicides” may have “information that proves to be critical for the homicide investigation.”

“We have reason to believe that after the homicides, teens that have not been accounted for may have been inside the home,” Washington said.

Police are asking parents in the area to question their teens and to come forward if they were at the house or contacted the suspects between April 1 and 8.

According to information released Thursday, Gwinnett police were called to Wendy and Randall Bjorge’s home often — 31 times between October 2015 and March.

“Out of that number,” Washington said, “we responded 18 times for runaway calls and at least eight times for check often as possible (calls) by request of neighbors. There were several other domestic dispute calls and illegal drug suspicion calls answered at the location.”

Cassandra Bjorge was known as a frequent runaway, authorities said. She and Rider face multiple charges in connection with the deaths.

Cassandra Bjorge was booked into the county jail Wednesday night on murder and aggravated assault charges. Johnny Rider was booked Monday on murder, aggravated assault and theft charges. Rider appeared in court Thursday.

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“This is a very unique and disturbing case on so many levels, and detectives are still exploring motive,” Washington said. “We may never find a scenario that makes sense to a reasonable person.”

Case timeline from Gwinnett County police:

6:09 p.m. April 6: Welfare check requested for 1911 Furlong Run by family member who had not heard from couple in about one week. Police responded, knocked on the door and found nothing suspicious.

8:19 p.m. April 6: COAP (check often as possible) requested at 1911 Furlong Run due to not having any contact with couple.

4:43 p.m. April 7: Welfare check requested for 1911 Furlong Run by family member who had not heard from couple. Police responded, knocked on the door and found nothing suspicious.

8:58 p.m. April 7: Missing person’s report filed by family members for Randall Bjorge.

8:30 p.m. April 8: Assault investigation at 1685 Rambling Woods Drive. Johnny Rider and an unknown female attacked Rider’s sister and her boyfriend. Wendy and Randall Bjorge’s vehicle found at the location.

11:13 p.m. April 8: Police force entry into 1911 Furlong Run and the two victims are discovered dead.

11:29 p.m. April 8: Johnny Rider and Cassandra Bjorge steal his sister’s vehicle from 1685 Rambling Woods.

3:57 a.m. April 9: Stolen vehicle found at 4025 McGinnis Ferry Road, building No. 800. Surveillance initiated on vehicle.

9:54 a.m. April 9: SWAT activation at 4025 McGinnis Ferry Road.

12:13 p.m. April 9: SWAT apprehends Johnny Rider and Cassandra Bjorge at the location and they are transported to the hospital with self-inflicted knife wounds to their wrists. They have since been treated, released and booked into the county jail.

What do you think?

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