The death of Special Warfare Operator First Class Tyler S. Stimson was a tragic accident that began as he prepared to jump from the top of the 259-foot tower with his parachute, investigators have determined.

Stimson, a U.S. Navy SEAL who performed BASE jumps in his spare time, was off balance at the time of his jump on Friday from the American Towers Inc. cellular service tower near the 4000 block of Godwin Boulevard, Suffolk spokesperson Debbie George said Monday.

George said investigators had determined that as Stimson fell, his legs got caught in the lines of his parachute, which would have caused it to fail to fully deploy.

A friend of Stimson’s, fellow SEAL Jason James Tompsett, had joined Stimson at the scene and reportedly had successfully made the jump before Stimson’s fatal attempt.

Tompsett has been charged with trespassing as a result of the incident. The cellular tower was clearly marked with “No Trespassing” and other warning signs and had a high fence topped with barbed wire around it.

George said police are still awaiting the results of a toxicology report from the coroner’s office, which performed an autopsy on Friday, but she added that they do not suspect foul play.

“There’s no question whether this was accidental or not,” she added.

Stimson, a Wakefield, N.H., native, was assigned to an East Coast-based SEAL team.

He was a highly decorated combat veteran of both Iraq and Afghanistan, according to a press release from the U.S. Navy. His awards and decorations include the Navy and Marine Corps Commendation Medal with combat “V” distinguishing device; two Combat Action Ribbons; the National Defense Service Medal; Afghanistan Campaign Medal; Iraq Campaign Medal; Navy Unit Commendation Medal; NATO Medal; Armed Forces Expeditionary Medal; Marksmanship medals for both rifle and pistol; and a multitude of personal, unit and campaign decorations.

The Navy has not released similar information about Tompsett.

Stimson, at least, had some experience with BASE jumping, which is defined as parachuting from a high structure or cliff and derives its acronym from Buildings, Antennas, Spans and Earth — the four types of objects that serve as launching points for BASE jumpers.

His Facebook page includes a video shot with a handheld camera of a jump from a tower similar to the one where Friday’s accident took place. That video, posted June 27, shows Stimson and a friend jumping separately, falling about halfway down the tower and then gliding to the ground under a parafoil chute. Both jumpers are on the ground in less than 80 seconds.

Stimson is survived by his wife Chelsey Stimson of Virginia Beach, his parents Linda and C. Thomas Stimson of Wakefield, N.H., and his sister Jessica of Denver, Colo.