ST. PETERSBURG — The mother of one of three teenagers who drowned in a stolen car in March announced Tuesday that she plans to sue the Pinellas County Sheriff's Office.

Yashica Clemmons and her attorney Aaron O'Neal announced the plans at a news conference called by the International People's Democratic Uhuru Movement, a longtime and often inflammatory critic of law enforcement. Clemmons is the mother of Dominique Battle, a 16-year-old St. Petersburg girl who drowned before dawn on March 31 when the Honda Accord she was in plunged into a pond in a north St. Petersburg cemetery.

"We believe these girls were murdered," said O'Neal, a Maryland attorney who serves as general counsel for the Uhurus. "We want to get to the facts and the truth about what really happened that day."

O'Neal did not specify what damages he will seek or what the lawsuit will allege, though he said a wrongful death claim is likely.

O'Neal said a portion of dash cam video released by the Sheriff's Office showing a deputy traveling at high speeds is evidence that deputies were chasing the Honda carrying Battle and her friends, 15-year-olds Ashaunti Butler and LaNiya Miller. A Sheriff's Office policy forbids deputies from pursuing stolen cars.

O'Neal said one deputy, Sgt. Howard Skaggs, might have used a "pit" maneuver, tapping the Honda with his car and causing it to veer into the pond. It's a claim the Uhurus and their chairman, Omali Yeshitela, made at a news conference last month, pointing to damage on the Honda's rear bumper as evidence.

"The three girls would have been alive today if (deputies) followed their own protocols around these police chases," O'Neal said.

O'Neal and other critics have also seized upon audio of deputies talking to one another after the car hit the pond. One says "they're done" and another says he thinks he hears screaming.

"We can see clearly from the video that there was no clear urgency to rescue those girls," O'Neal said.

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Sheriff Bob Gualtieri calls the claims "ridiculous."

"If they think they've got a viable claim, bring it and stop doing press conferences ," Gualtieri said Tuesday. "There was absolutely zero wrongdoing on the part of the Pinellas County Sheriff's Office. They've presented no facts or evidence."

Gualtieri said the speeding deputy was trying to get to the scene, not following the Honda. He has said deputies directly behind the Honda were keeping the car in sight until someone bailed out on foot or the driver turned around to exit the cemetery.

Gualtieri said none of his agency's cars struck the Honda. Two deputies on the scene tried to wade into the dark, mucky pond as the car sank but turned back because the conditions were too dangerous. The dark tint prevented the deputies from seeing who was in the car, he said.

The dash cam footage does not show rescue attempts or capture any conversations about rescue efforts. But it does show some deputies, without uniforms or belts on, heading to and from the water.

The Sheriff's Office has said it's unclear who was driving the Honda. Miller and Butler were found in the back seat. Battle's body was found lying over the center console with her legs in the back seat and her head and torso on the driver's seat.

Gualtieri said the responsibility for the incident rests squarely on the shoulders of the driver who refused to stop when a sheriff's sergeant who spotted the car driving without headlights activated his emergency lights. The girls' guardians, Gualtieri said, also bear some blame for failing to keep track of children who had already racked up several auto theft charges.

Critics have tried to refute that characterization.

"Dominique was a caring, loving child who was loved by her mother, her family, her friends and her neighbors," Yeshitela said.

A tearful Clemmons read a letter she said her daughter sent her while being held in a juvenile detention center.

"You never gave up on me even when I gave up on myself," she wrote. "It's time for a change. Enough is enough. I just want to get help because I know I'm not going to be able to stay on track if I do it by myself. I just get influenced easily. It don't have nothing to do with how you raised me. I'm just growing up, trying to see how I fit in. You really are a good mom."

"Justice will prevail," Clemmons said afterward when asked if she had a message for Gualtieri. "What you did in the dark will come to light. Now we have the whole world looking at you and we're coming."

Others have also questioned the Sheriff's Office actions that night but have sought to distance themselves from the Uhurus and their claims.

Michele Whitfield, a Clearwater lawyer representing Miller's family, said she is still working to secure materials from the Sheriff's Office as part of her own inquiry and is not affiliated with the Uhuru group.

"We are taking the time to make sure we have a full and complete investigation and all the evidence so we'll be best prepared to file a lawsuit should that time come," she said.

Maria Scruggs, president of the St. Petersburg branch of the NAACP, said her group has also requested records to review the incident and has not been in contact with the girls' families. The group is also reaching out to local authorities and the Department of Juvenile Justice to figure out a way to tackle the epidemic of teens stealing cars, Scruggs said.

"To see if we can proactive in trying to prevent this kind of travesty in the future," she said.

Contact Tony Marrero at tmarrero@tampabay.com or (813) 226-3374. Follow @tmarrerotimes.