The son of the Tennessee woman who suffered a "horrific" drowning death in the back of a police car is now suing the department for $10 million dollars. 

Tabitha Smith, 35, was killed last month when deputy R.J. Leonard, 35, drove his police cruiser into the Tennessee River while she was handcuffed in the backseat. Moments before the vehicle crashed Leonard texted his wife, celebrating his first arrest, according to District Attorney Russell Johnson.

Leonard worked in construction for most of his adult life, until he moved to Tennessee to "pursue his dream of becoming a police officer," his family wrote in his obituary.

Smith's adult son, Nathan, is now suing Leonard's employer, Meigs County Sheriff's Office, alleging that the deputy was not properly trained or supervised.

"As a direct and proximate result of the acts and omissions of Leonard and the County, the Deceased suffered a horrific death," the lawsuit alleges.

The lawsuit cites several alleged deficiencies in Leonard's training, including the fact that he "was not properly trained or supervised by the County to refrain from the use of his cell phone while transporting an arrestee in a patrol vehicle" and was incapable of ensuring "the safety of the Deceased while in his custody."

Additionally, the lawsuit claims that Leonard received inadequate information regarding his assigned area of patrol - where there was "a history of other people driving into the Tennessee River."

Smith allegedly tried to warn Leonard when he was driving towards the river, according to WBIR.

Nathan Smith is seeking a jury trial to determine whether Leonard and the county are responsible for the deprivation of liberty interest and bodily integrity, wrongful death, battery and assault claims, intentional infliction of emotional distress, gross negligence, loss of consortium and two violations of Tennessee code.

In addition to her adult son, Smith was also survived by three minor children, according to her obituary.