Amy Senser admitted she was driving the vehicle that killed a Minneapolis chef only after her stepdaughter threatened to tell police, a prosecutor said during opening statements Monday in Senser's trial.

Assistant Hennepin County Attorney Deborah Russell said Brittani Senser, the 28-year-old daughter of former Minnesota Vikings star Joe Senser, became concerned that she was a suspect in the hit-and-run crash that killed Anousone Phanthavong, 38, of Roseville. The Sensers' attorney, Eric Nelson, directed authorities to the Mercedes-Benz SUV the day after the Aug. 23 crash, but didn't say who was driving until nine days later.

"'You tell the State Patrol who the driver is or I will,'" Russell said Brittani Senser told Nelson on Sept. 1. The next day, Russell said, Nelson faxed authorities a notarized admission by Amy Senser that she was the driver that night.

Both Brittani and Amy Senser, of Edina, are scheduled to testify at the trial.

The Senser trial began succinctly Monday, as each side delivered opening statements reiterating their positions taken since Senser, 45, was charged eight months ago. She faces three felony counts of criminal vehicular homicide -- one for leaving the scene, a second for failing to call for help, and the third for negligence. The jury may also consider a lesser charge of careless driving.

Amy Senser to testify

While Russell said cellphone records, deleted text messages and witness statements place Senser in the area after Phanthavong was killed, she did not reference impairment by drugs or alcohol, or any other motive for Senser to leave the scene.

Nelson maintained that Amy Senser didn't know she had hit someone that night when she became lost en route to picking up her two teenage daughters and their two friends from a Katy Perry concert at the Xcel Energy Center in St. Paul. Her actions that night were not those of someone who knew they had hit someone, he said, adding that prosecutors can't prove she was negligent when she struck Phanthavong as he filled his stalled car with gas on a darkened freeway ramp that Nelson claims was cluttered with construction debris. Phanthavong was a chef at a nearby Thai restaurant.

Senser, who had a history of migraine headaches and had just been diagnosed with a sinus infection, had to leave the concert early, Nelson said. She was in the process of turning back to St. Paul when she left westbound I-94 at the Riverside Avenue exit and struck Phanthavong without realizing what she had done, he said.

"You will hear from Ms. Senser what she heard and what she felt when she got off that exit," Nelson said.

Russell countered that crash reconstruction experts will intricately lay out details of how the exit ramp was configured that night, namely the construction barrels and cones that Senser's attorney claims she believes she struck.

"You will see where there were barrels, and most importantly, where there were not any barrels," she said.

'Tragic' decision

Although both sides promised lengthy testimony, their opening statements were brief. Russell's lasted about 10 minutes, while Nelson's lasted about 15.

During morning jury selection, eight men and six women, including alternates, were chosen. All but two are white and range in occupation from cemetery manager to welder and nurse. Most were somewhat familiar with the case and knew of Joe Senser, but said they could remain impartial. Others, including a woman who was incredulous as to how Senser could fail to know that she had struck someone, were dismissed.

A few supporters of Senser sat in the front row, but her husband, daughters, ages 14 and 15, and stepdaughters were absent because they are sequestered as witnesses.

Nelson said Amy Senser surprised her teenage daughters and two friends with the concert tickets the morning of Aug. 23, with a plan to meet the girls at the concert after she finished work. Nelson said Senser's phone records for the next two hours are consistent with that plan, until she called her husband to pick up the girls because she felt sick.

"That decision," Nelson said, "was tragic, and was how the lives of Ms. Senser and Mr. Phanthavong became permanently intertwined."

That night, Joe Senser arrived with the girls at their Edina home to find the Mercedes SUV parked in the driveway "for all the world to see" while Amy Senser sat a few feet away. He said none of the girls will testify that she acted impaired or smelled of alcohol.

Russell said Brittani Senser will testify that when she and her fiancé met the Sensers for coffee last December at Southdale Mall, her fiancé asked Amy Senser how the case was proceeding. She allegedly told him how a witness reported that an SUV driver who allegedly returned to the scene, driving erratically, was a blonde, implicating Senser's other stepdaughter, Ashlee, 26.

"She doesn't even live here," Amy Senser allegedly said, laughing. Witnesses for the prosecution will take the stand Tuesday morning.

Staff writer Matt McKinney contributed to this report. Abby Simons • 612-673-4921