A Seattle teen suspect could receive a reduced prison sentence if the case remains in juvenile court

The 15-year-old boy accused of killing his parents and three siblings at the family’s mansion in Washington state could spend less time behind bars if his case doesn’t go to adult court, prosecutors said .

The unidentified teenage suspect can only be held until he is 25 years old — less than a decade from now — if he is convicted in juvenile court, according to the King County Prosecutor’s Office.

Prosecutors argued Friday that the gruesome case should be tried in adult court teen faces life in prison for alleged shooting his parents – Mark, 43, and Sarah Humiston, 42 – his two brothers and sister, aged 7, 9 and 13, dead, with his 11-year-old sister injured in a bloody massacre on Monday.

Defense attorney Amy Parker described the alleged teenage killer as a caring boy who has no criminal record and enjoys mountain biking and fishing.

“We want the court to know that we have been contacted by several people in the community who know our client and have testified to his good character,” she said in court Friday.

“He is described by them as friendly and caring. This is a boy who has many friends, pro-social interests and has made a positive contribution to his community.”

Substitutes responded to the Lake Alice Road home around 5 a.m. Monday and found the victims’ lifeless bodies covered in blood and riddled with bullets to the face, head and body in the family’s $2 million home in Fall City, according to charging documents obtained by the Post.

The teenager is accused of hatching a disturbing plot to stage the massacre as a murder-suicide carried out by his 13-year-old brother and be the family’s sole survivor, according to charging documents.

The report claims the 15-year-old tried to say his brother, who was murdered, had gone on the murderous rampage after being caught watching porn the night before.

Detectives also allege that the accused teen killer attempted to stage the crime scene to make it appear as if his brother committed the heinous act and ‘planted’ a gun in his hand after he was killed.

The The suspect’s 11-year-old sister, the only family member to survive the massacresaid her brother used her father’s silver handgun to fatally shoot her parents, her brothers, Benjamin and Joshua, and her sister Katheryn, according to charging documents.

According to the documents, the teenager’s murderous rage came after he failed a number of exams at school and got into ‘a lot of trouble’.

The young girl was sleeping in her room when she woke up to the deafening sound of gunfire.

She tearfully told investigators that her older brother burst into her bedroom and allegedly opened fire on her, hitting her in the hand and neck, and allegedly killed their younger sister, with whom she shared a room.

The girl then “pretended to be dead” when her brother reentered the room and stood next to her bed before he came back into existence, according to charging documents.

She fled the house through her bedroom window when she felt her brother would not catch her and ran to a neighbor’s house, where she called the police.

Officers responded to the family home, about 30 miles (48 kilometers) outside Seattle, after receiving 911 calls from the alleged killer and his surviving sister, according to the documents.

The wounded girl, who was taken to Harborview Medical Center After the massacre, she identified her 15-year-old brother as the shooter.

Officers immediately took the minor into custody after discovering the bodies and his sister identifying him as a suspect, prosecutors said.

The teen was charged with five counts of first-degree murder and one count of first-degree murder and is being held at the Clark Child and Family Justice Center in Seattle.

A judge is expected to make a decision on which court will try the teen during a hearing on Jan. 8, 2025, prosecutors said.