The 15-year-old boy who killed his parents and three siblings in Fall City, Washington tried to frame his brother for the heinous crime by claiming the slaughter was part of a botched murder-suicide pact.

Software engineer Mark Humiston, 43, and his registered nurse wife Sarah, 42, were found deceased at their luxury $1.4million home in the leafy town 30 miles from Seattle along with three of their five children. 

The couple were extremely religious and imposed a highly-controlled existence on their five children – including dictating who they could be friends with and homeschooling them.  

Their eldest son was arrested at the scene and is now facing five first degree murder charges and one attempted murder, with an arraignment scheduled for Friday.  

A police report obtained by DailyMail.com shows the teenager attempted to blame the murders on his 13-year-old brother Benjamin, claiming he shot the family and killed himself after being caught watching porn the previous evening. 

But police say the 15-year-old killed his family himself using his father’s Glock handgun, with his younger sister, 11, saying it was the eldest brother who fired two shots at her, hitting her in the neck and arm. 

DailyMail.com has obtained the first photo of the accused killer son and is preserving his identity, pending his court appearance

Mark Humiston, 42, his wife Sarah, and three of their five children were shot dead inside their home in Fall City, Washington on October 21. The couple are pictured in 2011

According to detectives, the 15-year-old also attempted to stage the crime scene to lend credence to his story that it had been a murder-suicide perpetrated by Benjamin. 

The report notes that a black Glock pistol had been placed in the child’s hand but forensic investigators spotted that the weapon hadn’t been fired and that blood splatter from a fatal wound to the boy’s face was in the wrong place.

DailyMail.com can also reveal that the 4.55am 911 call that led to the grim discovery was placed by the teen from a bathroom in the house.

The 11-year-old survived the massacre by running to a neighbor’s home but the youngest Humiston children – 9-year-old Joshua and 7-year-old Katheryn – also died. 

The family, who were initially reported to have been found in their beds, were found scattered throughout the house with Mark found on the floor at the bottom of the stairs and Sarah ‘folded over’ over in her ensuite bathroom. 

Mark suffered four gunshot wounds while Sarah was discovered with two bullet wounds to the head.

A photo obtained by DailyMail.com shows all five children during happier times, splashing about on the lake with their father next to the home they had lived in since 2019 when they moved to Washington from Texas.

Other pictures show the 15-year-old, who was described by his lawyer as being a fan of fishing and mountain biking, playing on a bike mounted on a surfboard.

Neighbors had described the quintet as ‘the perfect family’ with soccer coach Rhea Robertson, who had mentored one of the victims, telling KOMO News at a vigil held on Tuesday night that the couple had been ‘dedicated’ parents.

She added: ‘Dad worked so hard, and mom was the most dedicated, loyal mother you could ask for.

‘You thought they were perfect. From the outside, they looked perfect to me.’

The couple’s eldest son, 15, (in green) is accused of killing his parents, two brothers, and one of his two sisters. The surviving sister, 11, (in red) was shot twice and is now in hospital. The siblings are pictured with their father during happier times 

The family was found Monday morning at their home in an idyllic Fall City neighborhood by Lake Alice, about 30 miles east of Seattle

Speaking to DailyMail.com, a neighbor who asked not to be named, said: ‘We used to see them riding their bikes around the neighborhood.

‘They were a nice family. We never noticed anything wrong or unusual. It’s a real tragedy.’

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But family insiders told DailyMail.com that their idyllic existence had a dark side, with the ultra-religious parents imposing a strict schedule on their five children and having extremely ‘high expectations’ of them.

The source described how the family maintained a small tight-knit circle and had caused some bad feeling in the community over the summer after ordering their eldest sons to stay away from the children of LGBTQ families living nearby.

‘It caused some disquiet,’ the source said. 

‘Mark found out that the boys had made friends with those kids and insisted they didn’t see them again. Everyone was quite upset about it.’

Nonetheless, when DailyMail.com visited the scene of the shooting this week, a makeshift memorial composed of huge bunches of flowers had been placed close to the home.

Police are still combing the property, with cruisers stationed close to the house while a mobile command center has been set up on a neighbor’s driveway.

The small community, which sits on the outskirts of Fall City, is set in a forested area around the shores of Lake Alice – a small 32-acre freshwater lake stocked with rainbow trout and Largemouth bass.

The home at Lake Alice Road is seen with police tape on Thursday after the mass shooting on Monday

Police are still combing the property, with cruisers stationed close to the house while a mobile command center has been set up on a neighbor’s driveway.

Homes in the area cost well above the national average of $300,000, with the median price of a property totaling an eye-watering $1.6million.

Locals described the area as ‘peaceful’ and told DailyMail.com that crime is a rarity.

One neighbor, who asked not to be named, said: ‘The last time anything happened was when someone stole mail from my mailbox and that was about five years ago.’

The Humistons had also been the victim of lumber theft shortly after they moved in in 2019, which prompted dad Mark to equip the home with security cameras.

Police on Tuesday said they had no subsequent records of call outs to the home since then and that none of the family had ever been in trouble with the law.

Court records obtained by DailyMail.com reveal the Humistons did have problems with a local builder who they sued in 2023 saying they had damaged their home during a remodel.

The remodel, which began in 2021 and cost $559,768, caused ‘extensive damage to the walls’ which subsequent repairs failed to fix.

The lawsuit, which was filed in January 2023, was settled by the warring parties in April the same year and dismissed.