Seattle teen suspected of fatally shooting parents, 3 siblings in ritzy suburb tried to frame brother, claiming he was caught watching porn: docs

The 15-year-old boy accused of murdering his parents and three siblings in the family’s Washington state mansion allegedly tried to frame his younger brother for the massacre, claiming he was caught watching porn.

The unidentified teen hatched a disturbing plot to stage the massacre as a murder-suicide carried out by his younger brother Benjamin, 13, to be the family’s sole survivor, according to charging documents.

The report claims that the 15-year-old tried to say Benjamin, who was murdered, committed the murderous rampage after he was caught watching porn the previous evening.

Detectives also allege that the accused teen killer attempted to stage the crime scene to appear as if his brother carried out the heinous act and “placed” a black Glock pistol in the 13-year-old’s hand after he was killed.

Forensic investigators, however, determined that the pistol had not been fired during the crime and that the blood splatter from Benjamin’s fatal wound did not match up with how his body was found.

Their parents, Mark, 43, and Sarah Humiston, 42, were highly religious and strict with their five children and decided who they could be friends with and homeschooled them, according to the Daily Mail.

The outlet also shared that police received a 911 call from the family’s $2 million house in Fall City at 4:55 a.m., on Monday.

The suspect allegedly called emergency services from a bathroom in the house.

The 11-year-old sister of the suspect, the only family member to survive the killing spree, said her brother used her father’s silver handgun to fatally shoot her parents, her brothers, Benjamin and Joshua, 9, and her little sister Katheryn, 7, according to charging documents released by the King County Prosecuting Attorney’s Office. 

According to the documents, the teen’s murderous rage came after he failed some tests at school and got into “a lot of trouble.”

The young girl was sleeping in her room when she awoke to the deafening sound of gunshots.

She told investigators that her older brother barged into her bedroom and allegedly opened fire on her, striking her in the hand and neck and allegedly killed their 6-year-old sister — with whom she shared a room.

Her brother then left the room and leaned over the three lifeless bodies in the hall to touch their necks and chests to “see if they were alive,” she recalled witnessing.

The girl then “pretended to play dead” as her brother re-entered the room and stood next to her bed before he exited again, according to the charging docs.

She fled the home through her bedroom window when she felt her brother wouldn’t catch her and ran to a neighbor’s house, where she phoned the police.

Deputies responded to the Lake Alice Road home, about 30 miles outside Seattle, around 5 a.m. after receiving 911 calls from the alleged killer teen and his surviving sister.

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

After discovering the bodies and his sister IDing him as the suspect, deputies immediately took the juvenile into custody, prosecutors said.

The teen was charged with five counts of first-degree aggravated murder and one count of first-degree attempted murder. 

He is detained at the Clark Child and Family Justice Center in Seattle and is due in court on Friday.