Background: The 900 block of South Deerfield Lane in Gilbert, Arizona (Google Maps). Inset: Rael Sanchez (Maricopa County Sheriff's Office).

A weekend evening at a family's home in Arizona turned chaotic when a relative of one of the homeowners shot his stepsister's boyfriend in the neck, authorities say.

Rael Sanchez, 21, stands charged with attempted second-degree murder, the Gilbert Police Department announced. The incident unfolded on Saturday at a home on the 900 block of South Deerfield Lane in Gilbert, Arizona.

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According to authorities, a teenage girl and resident of the house had her 16-year-old boyfriend over at the same time that Sanchez — "a relative of one of the homeowners" — was visiting. Sometime before 8 p.m., the couple was in the girl's room when Sanchez walked in and asked the boyfriend if he had his phone number.

He didn't, and he told him no, the girl recounted in court documents reviewed by Arizona's Family, which includes CBS affiliate KPHO and independent station KTVK. When the boyfriend asked Sanchez if he wanted his number, the defendant laughed and left.

The couple also left, going outside to a nearby basketball court, but as they walked outside behind the home, she saw Sanchez talking with another family member. Sanchez walked up to the couple, and the girl could see a gun in his waistband, according to police.

The suspect was reportedly behaving oddly, slurring his words and trying to antagonize the boyfriend, making comments such as "you ain't s—" and "you ain't about s—." The girl said she walked inside and told her family members about her stepbrother's actions, but they told her Sanchez was just "checking" the boyfriend.

Sanchez and the boyfriend were still talking when she rejoined them, per the local news source. The suspect was holding a bag and repeatedly saying "take me to Asia." The girl said her boyfriend looked scared.

The couple walked back inside, but still, Sanchez reportedly kept his focus on the boyfriend. As they walked, the girl recalled hearing a loud "pop" sound and then seeing her boyfriend fall to the floor.

The suspect allegedly ran away from the house and then drove away in his father's pickup truck. Gilbert police officers were called, and they arrived at the home to find the victim with "serious injuries." He was brought to a nearby hospital in critical condition.

Authorities were unable to find Sanchez until the following morning, when Phoenix police officers reported seeing him in the city. Once detained, he was brought to an area hospital for injuries that are unclear, and once he was released, Gilbert police officers took him into custody.

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Family members have said they believed Sanchez was experiencing mental health issues prior to the shooting. He was placed into the Maricopa County Jail under a $1 million cash-only bond.

The boyfriend was shot in the neck, with the bullet damaging his spine, the Arizona's Family story said. When he woke up in the hospital, he reportedly couldn't feel his arms or legs, and hospital workers told police he would likely be paralyzed if he survived the shooting.