MALIBU (CBSLA) — Friends and family of a missing 21-year-old Simi Valley man are wondering why he suddenly disappeared.

And they want to know if his disappearance is the latest in a growing list of unexplained violence in the Malibu area.

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KCAL9’s Peter Daut reported from the Lost Hills Sheriff’s Station. Meanwhile, many people are asking — where is Matthew Weaver?

Investigators are trying to answer that very question.

“I can’t rest until I find out what happened to him or where is he? This has been the biggest nightmare,” says Brooke Tipton, Weaver’s stepmother.

Nearly three weeks after Weaver mysteriously disappeared in Malibu Canyon, his family is still desperate for answers.

“My biggest fear is never finding him and never knowing what happened to him,” Tipton says.

Weaver was last seen Aug. 10 near a hiking trail at Stunt and Saddle Peak Roads.

The same night he vanished, a witness called 911 after hearing someone in the area screaming for help.

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But first responders were unable to find anyone. They did later find Weaver’s grey BMW, left behind up a remote trail.

“Why he would go down this road is beyond me,” Tipton says.

Multiple searches, both in the air and on the ground, have come up empty and Weaver’s family is growing increasingly frustrated, especially since the area has been recently plagued by unexplained violence.

In June, a 35-year-old man was shot in the head at Malibu Creek State Park while his daughters slept in a tent they were sharing.

Two other bodies were also recently dumped along roadsides and other people have disappeared in the same area.

Weaver’s loved ones can’t help but wonder if there’s connection.

“At this point we know something happened to him. or he’d be around,” Tipton says.

Weaver’s family says he often drove to Malibu for fun but they have no idea why he would have ever gotten out of his car.

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Investigators are asking anyone with information on his whereabouts or any other recent crime in the area to give them a call.