Scuba instructor arrested for 12-year-old North Texas girl’s death
TERRELL, Texas - The man who was leading a North Texas scuba certification class when a 12-year-old girl died last summer is now facing charges.
Scuba Instructor Arrested
William Armstrong (Kaufman County Sheriff's Office)
What's new:
William Armstrong was arrested on Friday and booked into the Kaufman County jail on an injury to a child charge.
His bond was set at $150,000.
The backstory:
Armstrong was the instructor for 12-year-old Dylan Harrison’s scuba certification class at The Scuba Ranch in Terrell on Aug. 16, 2025.
According to witness affidavits obtained by the family's attorney, there were eight students, an instructor, and a dive master in the class.
During the class, Dylan went missing. Her body was later found away from the platform at a depth of about 45 feet, according to the family's attorney.
The family has questions about why witnesses claimed Armstrong, a Collin County assistant chief deputy, was out of the water and "bone dry" as they began searching for Dylan and why crucial data from dive computers was never collected. One of those dive computers is now lost, according to the attorney.
Armstrong resigned from his position with the Collin County Sheriff’s Office in October. He was also "permanently suspended" from teaching classes at The Scuba Ranch.
Records obtained by FOX 4 showed that on the day before Harrison’s death, Armstrong worked a full day as a deputy, and then a full overnight security shift at an investment firm.
Family’s Lawsuit
PREVIOUS COVERAGE: Parents sue scuba agencies after 12-year old drowns
The parents of 12-year-old Dylan Harrison filed a lawsuit against two major scuba agencies alleging that systemic safety failures led to her drowning during a North Texas certification class. FOX 4's Lori Brown has more.
Big picture view:
Earlier this week, the parents of 12-year-old Dylan Harrison filed a lawsuit against two major scuba agencies, alleging that systemic safety failures led to her drowning during a certification class on Aug. 16, 2025.
The lawsuit alleges systemic safety failures in the self-regulated industry led to Dylan Harrison's death at The Scuba Ranch in Terrell.
The 40-page suit details multiple failures that the lawsuit claims are the result of the scuba diving industry turning a blind eye to safety failures for years.
Past coverage
- Crucial evidence 'lost' in scuba death investigation of North Texas 12-year-old, lawyer says
- Scuba expert who witnessed NTX 12-year-old's death questions ongoing investigation
- Scuba expert says NTX 12-year-old's death highlights risky training practices
- Instructor 'permanently suspended' after 12-year-old North Texas girl's scuba death
- Owner of dive shop in 12-year-old’s death seemingly admitted to past fatalities on video
- Instructor resigns from Collin County Sheriff's Office following 12-year-old’s scuba death
- NTX scuba death: Former deputy worked all day, overnight before instructing class, officials say
- Lawsuit claims 12-year-old’s scuba death was preventable, cites "flippant" scuba industry safety concerns
The Source: FOX 4's Lori Brown gathered information for this story from the Kaufman County Sheriff's Office, the Harrison family's attorney, interviews with witnesses and dive experts, and past news coverage.