Mark and Sarah Humiston
Two adults, identified as parents Mark and Sarah Humiston, were allegedly shot to death alongside three of their children early Monday morning, according to authorities.

The Washington teen accused of killing his parents and siblings may have been "in a lot of trouble" over receiving some failing grades at homeschool before "systematically" gunning down his five family members, say court documents.

The 15-year-old suspect, who the Lawyer Herald is not naming due to his age, was charged in juvenile court with five counts of first-degree premeditated domestic violence murder and one count of first-degree premeditated attempted murder with a firearm enhancement Thursday, court records indicate.

He has not yet entered a plea to the charges.

His 11-year-old sister was the sole survivor of last week's deadly rampage at their family's upscale Fall City, Washington home, where he allegedly fatally shot the victims, identified as their father and mother, Mark and Sarah Humiston, ages 43 and 42, respectively; and their siblings: Benjamin Humiston, 13; Joshua Humiston, 9; and Katheryn Humiston, 7, according to the King County Medical Examiner.

The 11-year-old victim called 911 from a neighbor's home after escaping from a "fire window" in her bedroom and told the operator she managed to survive by playing dead after being shot twice in the neck and hand.

Before the alleged gunman pulled the trigger, she said she recognized him as her oldest brother, who had recently been "in a lot of trouble" over his grades, according to court documents obtained by CNN. She said she also recognized the murder weapon: their father's Glock handgun that was kept in a safe that only the eldest sibling had access to, apart from their parents.

But seven minutes prior to her 911 call, her brother also spoke to dispatch.

In a frantic call for help, the teen alleged he was hiding in a bathroom after his 13-year-old brother murdered their entire family and turned the gun on himself, court documents stated, according to the network. He claimed his brother was in trouble after getting caught looking at porn, and that it may have motivated him to kill.

However, further investigation allegedly indicated the 15-year-old suspect "systematically murdered" his parents and three siblings, tried to kill a fourth sibling, and "staged" the murder scene in an attempt to pin the massacre on his younger brother, according to the documents.

During his preliminary hearing Tuesday, defense attorney, Amy Parker, told the court, "We want the court to know that our client is a 15-year-old boy who enjoys mountain biking and fishing and has no criminal history," KING-TV previously reported.

The 11-year-old victim was admitted to Harborview Medical Center in Seattle, but has since been released.

A family member is caring for her, as well as the teen in custody, King County Council member Sarah Perry said, according to CNN.

Meanwhile, a hearing on whether the suspect will be tried as an adult is slated for June 2025.

Originally published on Lawyer Herald.