SPRING LAKE — Michael and Tracy Arnold loved to zoom around the rural roads and paths of southeastern Hernando County with horsepower at the their fingertips.

On Thursday night, authorities say, the couple died together in a violent collision between her dirt bike and his all-terrain vehicle on a two-lane road, a short distance from their home.

The crash happened about 9:35 p.m. on Hayman Road east of Deepwell Drive, according to the Florida Highway Patrol.

Tracy Arnold, 40, was riding her YZ85 Yamaha dirt bike in one direction while Michael Arnold, 36, was riding a Yamaha Banshee ATV the opposite way, according to an FHP incident report. The vehicles collided — nearly head-on — and both riders were thrown from their vehicles. Both died at the scene.

Neither was wearing a helmet.

FHP Sgt. Steve Gaskins said troopers were still investigating Friday and that some basic questions remained unanswered. Investigators had not confirmed which direction each of the Arnolds was traveling at the time of the crash. Alcohol had not been ruled out as a factor. Toxicology tests were pending.

The Arnolds married in 2006, a relationship that started "perfectly," said Tracy's older brother, Steve Gorin. But the marriage recently had become tumultuous, and they were likely headed for divorce.

"It was a rocky relationship toward the end," said Gorin, who lives in Port Orange and drove to Hernando County after getting word of the crash early Friday morning.

There were also indications the couple had argued before the crash. Text messages Tracy sent to a family member indicated Michael left the house without her, Gorin said. Family members think Tracy got on the Yamaha at some point and headed west on Hayman Road, perhaps to look for him.

The crash happened on a straight stretch of road about a quarter-mile west of their Florida-style ranch home. The Banshee had a headlight; the Yamaha did not, Gorin said. Gaskins said a streetlight near the crash site appeared to be working.

Gorin said authorities told him his sister's injuries were most severe on the left side of her body.

Michael Arnold's parents also live on Deepwell Drive. A man at the house who identified himself as Michael's brother declined to comment to a Times reporter and said his parents did not want to comment, either.

Tracy Arnold was born and raised in California, lived in Port Orange for a while and moved to Hernando several years ago because her first husband worked there, Gorin said. She has two daughters, ages 16 and 21, from a previous marriage.

She enjoyed taking road trips on her Yamaha R1 street bike. Gorin had a similar bike, and he has fond memories of cruising with his sister over the Sunshine Skyway and heading to Bike Week in Daytona Beach.

"Free-spirited, strong-willed and very driven," Gorin said. "She definitely was not one to back down from anything, ever."

Arnold worked as a court specialist in the mortgage foreclosure section of the 6th Judicial Circuit's Dade City office, circuit spokesman Ron Stuart said. She was promoted last month to the position of court specialist II.

"The entire staff of the 6th Judicial Circuit is shocked and saddened by this sudden loss of a member of our work family," said Gay Inskeep, trial courts administrator for the circuit. "She was an asset to our team and a joy to know."

Staff writer Danny Valentine contributed to this report. Reach Tony Marrero at tmarrero@tampabay.com or (352) 848-1431. Follow @tmarrerotimes on Twitter.