The parents of a Missouri woman who drowned when she drove her car into a river plan to sue the police department after questioning why cops didn't arrest her when they pulled her over earlier in the evening.

Toni Anderson, 20, died after she drove her car into the Missouri River in January with cocaine and amphetamine in her system.

Kansas City police had pulled her over just hours earlier, after they found her sitting in her car in the wrong lane on a two-way street.

In a dash-cam video of the confrontation, the officer says to Toni: 'This is a two-way street. You're on the full left-hand side of the street, heading into oncoming traffic.'

Toni Anderson died after she drove her car into the Missouri River in January. Toxicology reports show the 20-year-old Wichita native had cocaine and amphetamine in her system

Toni's mother, Liz Anderson (right) says the family plans to sue over her death which she believes could have been prevented

Investigators found Toni's car (pictued) in the Missouri River two months after she disappeared

The officer doesn't arrest Toni but told her to pull into the gas station to 'sit there a while, gather yourself.'

Its unclear who Toni's parents are suing, but they have been critical of what happened in the hours before her death in the past.

Surveillance video from the QuikTrip gas station she pulled into was released in late June.

QuikTrip surveillance video shows Toni driving the wrong way and sitting at an intersection for nearly 15 minutes before a North Kansas City police officer pulls up behind her.

Another surveillance camera inside the store shows the 20-year-old walking around QuikTrip after having been pulled over, purchasing something, walking out and then driving off.

It was the last time she would be seen alive.

Toni walks around the QuikTrip after being pulled over by police, it would be one of the last times she would be seen alive

Liz Anderson, (left) the mother of Toni Anderson (right) is planning to sue over her daughter's death

She also had sent a text to a friend saying she had been pulled over.

Her body would be discovered two months later.

Toni's body was found submerged in her vehicle near a Parkville, Missouri, boat ramp.

A medical examiner said her hypothermia and drowning death was accidental and involved drug intoxication.

TONI ANDERSON'S EXCHANGE WITH KANSAS CITY OFFICER Officer: You are heading the wrong way. Anderson: Yeah, I know (inaudible). Officer: No, no. This is a two-way street. You're on the full left-hand side of the street, heading into oncoming traffic. Anderson giggles Officer: Huh? Not funny. Anderson: I'm sorry. Officer: That is why I'm asking you if you have been drinking. Are you taking any medications or anything? Anderson: No, I am just really sick. I don't feel good. The officer then walked to his patrol car to check Anderson's driver's license and plate. When he returns, he tells her: Toni, do me a favor, pull into that parking lot; sit there a while, gather yourself. So when it clears, I'm going to make sure the light turns. Go over there, park and sit. Anderson: OK, thank you. Advertisement

Liz Anderson, Toni's mother, says she wishes the cop would have given her a field sobriety test and arrested her daughter.

'I can't say too much, but shame on him,' she said. 'He could have saved my daughter's life. She was hammered. And going the wrong way. Any idiot could say, 'You're messed up.' '

'I feel he was probably giving her a break,' Liz Anderson said. 'But that isn't what you need to do — you need to serve and protect.'

Failed to arrive: She left her job at Chrome (left) before she was stopped a short time later by a police officer who pulled her black 2014 Ford Focus over on 9-Highway near a QuikTrip gas station (above)

January disappearance: Authorities say Anderson drove from her job at Chrome before she was pulled over by a police officer around 4am. The officer then directed her to a nearby gas station, where she was last seen alive

Jim White, a public safety lecturer at Indiana University and former member of the Indiana State Police, spoke to the Kansas City Star. White said instructing Toni Anderson to park 'implies the officer believed there was impairment or mental confusion.'

Police had initially denied Toni was pulled over, but eventually admitted she was stopped by a North Kansas City officer that night.

Investigators found the vehicle, a 2014 Ford Focus, near Anderson's last known location on her cellphone.

'We just got the news, there's a body in her car,' the woman's mother Liz told the Kansas City Star, sobbing when they located her vehicle. 'There is somebody inside.'

Anderson's family had hired private investigators who used sonar to find the car.

The young college student had been driving to meet with friends downtown after leaving her job at Chrome entertainment bar on 40-Highway around 4am.

Moments later, she disappeared, her car GPS failed and her cellphone 'went dark'.

Text messages show Anderson had messaged her friend Roxanne Townsend at 4.42am saying: 'Omg I just got pulled over again'. Townsend said her friend 'got pulled over all the time'.