A 15-year-old suspect was charged with killing all but one member of his family members in their Washington state lakefront home in October, and his defense team recently denied accusations that they altered the crime scene during their search of the house. 

Authorities discovered the deceased bodies of two adults and three children at the house in Lake Alice, Washington, on Oct. 21, and they immediately took the 15-year-old into custody, police said. 

The King County Medical Examiner’s Office identified the victims as Mark Humiston, 43, Sarah Humiston, 42, and their children, Benjamin, 13, Joshua, 9, and Katheryn, 7. A judge prohibited the media’s release of the teen suspect’s identity, though he is named in court records. 

The suspect’s 11-year-old sister survived the attack after she “closed her eyes and held her breath and pretended to play dead” and then escaped through a “fire window” in her bedroom, according to court records. 

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Several members of the suspect’s defense team were granted a 10-hour window on Oct. 29 to take pictures and conduct a 3D scan inside the Humiston home. 

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Last month, prosecutors alleged there was evidence that the teen suspect’s defense team “search exceeded beyond what was permitted,” and they accused those involved in the Oct. 29 search of moving items at the crime scene and removing one item from the crime scene entirely, before ultimately retracting their claims, according to court documents obtained by Fox News Digital.

Prosecutors said the King County Sheriff’s Office documented the home before and after the defense team’s access, and they originally alleged that a bottle of Clorox wipes from the home was missing and backpacks belonging to the child victims were opened or moved. 

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A few days after the Oct. 29 search of the crime scene, the suspect’s attorneys at the time – Amy Parker and Molly Campera – filed a notice to the court that they were withdrawing from the case. A new attorney, Kristen Gestaut, was appointed to represent the suspect “due to staffing shortages at all public defense divisions,” according to recent court records filed by the new defense. 

Gestaut has since filed a 31-page brief denying the state’s accusations against the previous defense team, arguing that the state committed “prosecutorial misconduct” and asking the state to publicly apologize to the suspect and his former defense team. 

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She claimed the prosecution made “false and defamatory allegations… irreparably damaging [the suspect’s] right to a fair trial.” 

The state then responded to Gestaut’s claims, withdrawing the accusations against the former defense team, adding that a “series of photos” was “missed,” according to court records. 

“The allegation made…that defense must have been responsible for moving the backpacks, and that the Clorox wipes were now out of sight, is therefore inaccurate and in fact contradicted by the available evidence,” the prosecution wrote in the response.

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In the early morning hours on Oct. 21, the suspect called 911, claiming his 13-year-old brother had killed his family. He sounded out of breath and said, “He just shot my whole family and committed suicide too,” according to an affidavit. 

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Detectives and prosecutors allege the 15-year-old suspect staged the scene prior to the arrival of first responders to make it appear that his young brother had committed the murders and then killed himself, according to an affidavit. The 13-year-old, Benjamin, was found with a gunshot wound to the head and a Glock in his left hand on his chest. 

During the suspect’s 911 call, police received another 911 call from a neighbor, who told authorities that the 11-year-old Humiston daughter had arrived at their home with gunshot wounds, telling them that her family members were all dead, and her 15-year-old brother was the one who shot them.

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The suspect was charged with five counts of first-degree aggravated murder and one count of first-degree attempted murder with a firearm enhancement, all of which have a domestic violence designation, the King County Prosecuting Attorney’s Office said. He is being held in secure detention at the Clark Child and Family Justice Center. 

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The 15-year-old did not enter a plea, pending the judge’s ruling on whether the case will be moved to adult court. The case will have a status conference on Jan. 8, 2025. 

The King County Prosecuting Attorney’s Office did not immediately respond to Fox News Digital’s request for comment. Gestaut did not have further comment.