(CBS/KPHO) A teenage boy allegedly strangled his mother to death in a family car before hopping into the driver's seat and ramming the vehicle into a pickup truck Wednesday morning, reports a Phoenix police spokesman.
"As we began to put all this together, suddenly the investigation switched from a fatal accident to a homicide investigation," said Sgt. Tommy Thompson.
According to Thompson, the boy's mother and 74-year-old grandmother were in their home state of Oklahoma before they drove to California to pick up the 16-year-old and his girlfriend to get the boy some help for his mental illness, reports CBS affiliate KPHO.
Police said as the grandmother was driving, the boy, who was sitting in the back seat, began to strangle his mother, who was sitting in the front passenger seat.
Around 4:00 a.m. the grandmother pulled into a convenience store in Phoenix, and asked the clerk to call police, Thompson said. The boy then suddenly got out of the back seat and jumped into the driver's seat. As he was speeding away in the car, the grandmother got into the back seat, according to Thompson.
An hour and 42 minutes later, police said the teen boy was speeding, passing vehicles and weaving in and out of traffic when he ran a red light and crashed the Ford Focus he was driving into a 1989 Chevy pickup truck.
Police initially thought the mother had died from injuries she suffered in the crash, but as the investigation unfolded, officers said they discovered that she had been choked to death prior to the collision.
"When you say strange, that is perhaps an understatement in this case," said Thompson.
The grandmother, the boy's girlfriend, and the 46-year-old male driver of the pickup survived the crash and all are expected to recover from their injuries, reports KPHO.
The boy is in the hospital recovering from injuries sustained in the crash. Police said he will face murder charges upon his release.