Warning: This story contains graphic content. 

SPOKANE, Wash. — Spokane Valley stabbing suspect Justin Robertson, who triggered an AMBER Alert in three states on Tuesday, was involved in a standoff that ended in his death from an apparent self-inflicted gunshot wound, authorities said.

Newly filed court documents are providing more information about Tuesday's stabbing and standoff.  

Spokane County Sheriff's deputies responded to a panic alarm at the home located at 12808 E. Blossey Avenue at about 5 a.m. on Tuesday.

When deputies arrived, they found the side gate wide open. They then knocked on the front door and heard a woman screaming for help, according to the sheriff's office.

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When deputies arrived at the home, they saw Robertson’s estranged wife lying in a pool of blood with at least three stab wounds, including one to the chest and two on the upper torso underneath an armpit, according to court documents.

Police said her injuries were serious but she is expected to survive. 

She said Robertson had tied her up with a cellphone charging cable in the master bedroom, where she later escaped.

Robertson’s wife told authorities that she recently served him with divorce paperwork.

Robertson's wife told authorities that after she was stabbed, he fled with their five-year-old son, according to court documents. An AMBER Alert was issued at 7:30 a.m. 

She also said that her estranged husband possibly left with two of her cellphones and two iPads, according to court documents.

Deputies did not find the knife used in the assault during an initial search of the home, but they did see drops of blood in the kitchen, a bloody palm print on the kitchen counter and blood on the door handle to the rear sliding door, according to court documents.

Deputies found cause to arrest Robertson for first-degree assault domestic violence and second-degree kidnapping, according to court documents.

At about 9 a.m. on Tuesday, U.S. Marshals went to a home owned by one of Robertson's family members in St. John, Washington, where they found Robertson’s red Subaru in an airplane hangar on the property, according to court documents.

According to court documents, one of Robertson's family members called a landline at the home and Robertson answered the phone. It appears that the communication occurred while U.S. Marshalls were at the home.

Robertson admitted to the family member that he spoke with on the phone that he had his son but said he would only leave the home if she arrived there, according to court documents.

A search warrant was filed for blood; trace evidence, including DNA, bodily fluids, fingerprints, hairs and fibers; cutting and stabbing instruments, such as knives; documentation left behind by Robertson; photos of the scene; items belonging to Robertson; two cellphone and iPads that could belong to Robertson’s wife; electronic devices; and items that Robertson could have used to restrain his wife.

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