LAKE MARY, Fla. -- A former Darmouth basketball player suspected of drowning his toddler daughter and attempting to drown his 4-year-old son killed himself Monday by swerving into the path of a tractor trailer, authorities said. His two other children were injured in the crash.

Police believe the drowning and crash that killed Bryan Christopher Randall are the result of a dispute with his estranged wife. In a suicide letter found in the wreckage, Randall wrote he wanted to kill himself and his children because he didn't approve of how his ex-wife was caring for them, authorities said.

"I would say this is a domestic situation gone very bad," Maitland Deputy Police Chief Gary Calhoun said.

Randall, a point guard, was the Ivy League's Rookie of the Year in 1985 and was a first-team all-Ivy selection in 1988. He finished his collegiate career as the school's all-time assists leader, with 488 in 98 games.

The crash happened about eight miles north of the small lake where Randall's 2-year-old daughter Yanna and 4-year-old son Regal were found Sunday morning by a fisherman. The boy was in serious condition Monday, and an autopsy was to be done on his sister.

Investigators said the crash occurred after Randall, in his sport utility vehicle parked on the eastbound shoulder of Interstate 4, made a hard left turn into the path of an oncoming truck hauling cars.

Randall was pronounced dead at Orlando Regional Medical Center, Lake Mary Police Chief Richard Beary said. Bryan, 8, also was in critical condition and Julian, 6, was in stable condition following the crash, hospital spokesman Joe Brown said.

"We are investigating this as a murder-suicide," Beary said.

Police said Randall picked up all four children Friday night and was supposed to return them Sunday night to his estranged wife, Lisa, but never did.

When the children were not returned, their mother contacted police Monday morning. She was taken to Florida Hospital Orlando, where she identified the two found in the lake.

The Randalls were married for nine years but began divorce proceedings in May, Calhoun said. Court records show Lisa Randall, 41, obtained a restraining order against her husband last month.

The small lake where Yanna and Regal were discovered is in an office park about six miles north of Orlando.