PHOENIX -- The parents of a 9-year-old boy who was shot in the head in their Phoenix home put off calling 911 as they cleaned up evidence in multiple rooms of the house, police said Wednesday calling it a case that “shocks your conscience.”

Wendy Lavarnia told police that her 2-year-old son found a gun left on a bed and accidentally shot his older brother Monday. Police cast doubt on her story as they launched a murder investigation against the 28-year-old woman and her ex-convict husband, Kansas Lavarnia.

Police began to become suspicious of the mother’s story when they found inconsistencies in her account and when the boy’s father showed up at the home with a crudely bandaged gunshot wound on his upper arm. The wound looked to have been punctured multiple times, possibly with a screwdriver, to camouflage the injury.

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Police declined to specify the mother’s inconsistencies or say who they think shot the boy and his father. It’s unclear whether the couple is now represented by lawyers who can speak on their behalf.

Authorities said the parents delayed medical care for their son to clean up evidence in the house. Police declined to say whether they believe the boy would be alive had authorities been alerted sooner.

But a probable-cause statement filed by police says the lack of visible blood and the extent of blood residue implied that a significant amount of time passed before authorities were called.

“We have a 9-year-old critically wounded, shot in the head, in dire need of lifesaving efforts and care, which was delayed and not provided to this young man,” police Sgt. Vince Lewis said. “It definitely shocks your conscience.”

In a press conference Wednesday, Phoenix police Chief Jeri Williams called the fatal shooting of the boy a “tragic death,” according to CBS affiliate KPHO.

According to the CBS affiliate, the 9-year-old has been identified as Landen Lavaria.

Landen Lavaria KPHO-KTVK-TV

Lewis declined to specify the efforts taken to clean up evidence in several rooms at the house.

The father’s appearance at the home three hours after officers started investigating was suspicious because he was injured, Lewis said. Police say they found evidence of blood in the trunk of the vehicle that Kansas Lavarnia drove to the house.

He is accused of first-degree murder, child abuse and hindering prosecution, while Wendy Lavarnia is accused of first-degree murder, court documents said. Prosecutors have not yet charged them.

In a court appearance before her son died, the mother asked a judge whether she could go to the hospital to see the boy, but the judge said she could not leave jail without posting bond. Kansas Lavarnia’s only statements in court were responses to questions about his name and date of birth.

They are now being held in lieu of $1 million bond each.

Kansas Lavarnia had originally been booked on weapons misconduct. He was barred from having a gun in the home because of three 2009 convictions for theft and possession of burglary tools. He completed a three-year prison sentence in 2012.

He blamed his convictions on a longstanding addiction to pain medications, saying he started taking the drugs after he broke his back in an ATV accident when he was 15, according to court records.

He said he was sober from 18 to 21 but later resumed using pain medications. Once such drugs got too expensive, he turned to cheaper illegal drugs, using cocaine and heroin for a few years, records say.

Neighbors of the couple said the children could sometimes be seen outside wearing only a diaper.

“Their kids were always running in the front with their diapers on,” said Marie Mosley, who lives next door. “They always yelled and cussed at them, which I didn’t think was right, to cuss at little babies like that.”

Mosley also was surprised when she saw the mother emerge from the house showing little emotion, considering her child had just been shot in the head and taken away by paramedics barely alive.

The couple’s three surviving children are in the care of the state’s child-welfare agency.

Lavarnia’s first conviction stemmed from a January 2009 arrest when he was seen crouched down in a car outside a home where $480 in property had been stolen. The victim recognized the driver as Lavarnia, who used to clean fish tanks for the victim, authorities said.

Seven months later, police say Lavarnia tried to steal a sports car in his apartment complex and used tools in a bid to tamper with the vehicle’s ignition.

A month later, Lavarnia used a friend’s stolen driver’s license to withdraw $4,500 out of his bank account, investigators said. Lavarnia told authorities he was abusing drugs at the time and wasn’t thinking clearly, court records said.