A 16-year-old Mesa boy accused of killing his mother and a 17-year-old accomplice will be charged as adults in the case, police said Monday.
The body of 36-year-old Tina Helms Spencer was found Saturday in a backyard shed at the family's property.
The victim's 16-year-old son, Michael Helms, was arrested Saturday. He was booked into jail on charges of first-degree murder of his mother, attempted first-degree murder of his stepfather, three counts of aggravated assault on the stepfather, concealment of a dead body and tampering with evidence.
On Sunday, the teen's friend, 17-year-old Christian Lee Blakely, was taken into custody and jailed on charges of first-degree murder, concealment of a dead body and tampering with evidence, said Mesa police Sgt. Tony Landato.
Both have been booked into juvenile detention.
Mesa police officials said they got a call about an altercation in the 2100 block of East Juanita Avenue. When officers arrived just before 4 a.m. Saturday, they found Spencer dead inside.
According to a court document, Helms intentionally struck his mother with a frying pan and hammer and choked her in a rage. The boy then moved the body and placed it in a back shed. Spencer's injuries were consistent with blunt force trauma, according to a probable cause statement.
Helms then waited for his step-father to return home, the court document stated. The boy hit him over the head with a frying pan and punched and choked him, according to the probable cause statement. The man was able to break free and call police.
Officers said they found the hammer and frying pans at the scene.Helms admitted to planning and preparing for the attack. He also admitted to cleaning up the scene and moving and concealing the body, the court document stated.
"We anticipate a transfer hearing in the near future where a court will decide if both will be charged as adults," police said in a statement released Sunday morning.
Landato said the 16-year-old had been getting into trouble at school and the mother and stepfather had disciplined him at home, including grounding him and taking away his cell phone. Landato said there was a "heated" phone call between the mother and her son the night before she was murdered.
Landato said investigators are still trying to piece everything together.
"It's certainly disturbing to think of the impact that this incident has had not just on the victims but on the parents of these juveniles and extended family and loved ones," Landato said.
Stay with cbs5az.com and CBS 5 News for updates on this developing story.
Copyright 2013 CBS 5 (KPHO Broadcasting Corporation). All rights reserved.