HONOLULU (HawaiiNewsNow) – Honolulu police arrested a man for negligent homicide following a jet ski crash at Keehi Lagoon that took the life of a 16-year-old Vacaville girl.

Tyson Dagley, 20, was arrested just before 10 p.m. Thursday at the Ala Moana Hotel.

On Sunday, Kristen Fonseca of Vacaville was riding a jet ski in Keehi Lagoon. Her stepfather says another watercraft that was traveling 40 mph slammed into her from behind.

“I looked over and I saw the other guy come in at a very high rate of speed on his jet ski, looking toward the dock. So he was not looking in front of him,” he said.

Canton said he shouted for the man to look ahead but it was too late. According to police, Dagely was the rider of that watercraft.

“He ran into the back of her jet ski. I noticed that she hit her head against the steering wheel and then she fell into the water,” he said.

Canton said he relives the scene “every day, every minute.”

A medical examiner says Fonseca died from brain injuries. She would have been a junior at Vacaville High School this year.

Dagley was charged with negligent homicide. His bail is set at $100,000.