The prosecution alleges Jorene Nicolas, 31, was so distracted while driving that she didn't notice traffic had stopped along the 405 Freeway in Westminster.
"She was driving over 85 miles an hour, not paying attention to completely stopped vehicles, and rear-ended the victim," said prosecutor Jennifer Walker.
Jurors were shown photos of the victim's crumpled Hyundai. Prosecutors say Nicolas's Toyota Prius slammed into the victim's car, pushing Deanna Mauer into the car in front of her before crashing into the center divider. The victim's vehicle then spun around coming to rest facing the opposite direction. The collision occurred around 11 a.m. on April 27, 2011.
"The defendant did not act how an ordinary careful person would in the same situation. She killed Deanna Mauer," said Walker.
Mauer, 23, was a star pitcher at San Jose State University. She died from her injuries that day. Nicolas has pleaded not guilty to felony vehicular manslaughter with gross negligence.
"The evidence will show that Ms. Nicolas was not inattentive on the day of this accident," said defense attorney Eric Lampel. "She was driving in the number 1 lane going with the flow of traffic, which was 70 miles an hour plus."
The defense alleges that Mauer swerved in front of Nicolas, and that the victim's brake lights either weren't working or she didn't apply them right before the crash.
"No one saw brake lights on the Hyundai driven by the decedent at any point prior to the time she swerved in front of Ms. Nicolas," said Lampel.
During opening statements Tuesday, the prosecutor did not tell jurors why Nicolas was so distracted, only that she didn't brake, she didn't slow down. Traffic had been stopped for at least 30 seconds before the crash.
The trial continues Wednesday. Nicolas faces six years in prison if convicted.