The 18-year-old Rohnert Park driver who killed a 2-year-old child and seriously injured her mother when she struck the pair as they walked in a crosswalk now faces a misdemeanor vehicular manslaughter charge, Sonoma County District Attorney Jill Ravitch said Monday.

Kaitlyn Dunaway, a freshman at Sonoma State University, was text messaging on her cell phone when she struck Calli Murray and her mother Ling Murray, who were crossing Snyder Lane, Ravitch said.

Investigators believe Dunaway was also driving at an unsafe speed and failed to yield the right-of-way to pedestrians in a crosswalk, Ravitch said.

"I can't get into the facts of the case, but she's alleged to have committed the charge in that she unlawfully and without malice killed this human being," Ravitch said.

Dunaway could face a maximum yearlong jail sentence plus probation if convicted, Ravitch said. She was cited by letter to appear in Sonoma County Superior Court at 8:30 a.m. Thursday to face the charge. She was not arrested.

News of the charge brought some measure of relief to the Murrays, said Al Andres, the toddler's grandfather.

"It's a step toward resolution for all involved," said Andres, who traveled to Rohnert Park from his home in Hartley, Del. so that he can attend Thursday's hearing.

Dunaway was behind the wheel of a 1997 Honda at about 5:30 p.m. Dec. 1 when she struck the mother and child, Rohnert Park Public Safety Department officials said.

Ling Murray held her child's hand as they walked through the crosswalk at Medical Center Drive, according to police.

Dunaway was traveling south on Snyder Lane when she struck them, police said. Calli Murray died at the scene.

Ling Murray suffered major injuries throughout her body, including fractures in her legs, arm and pelvis. She underwent a series of surgeries followed by weeks of recovery at a Petaluma rehabilitation hospital before she was able to return home March 10.

Rohnert Park detectives filed their investigation with the District Attorney's office in January, police officials said. Prosecutors reviewed the report and allege that Dunaway failed to yield the right-of-way to the mother and child because she was using her cell phone, Ravitch said.

When asked what led prosecutors to charge Dunaway with a misdemeanor and not a felony, which could involve a prison sentence, Ravitch said she couldn't easily explain the difference because "it's complicated whenever you look at a set of circumstances."

"All I can tell you that we felt given the state of the evidence, we felt this was the appropriate charge," Ravitch said.

In most cases, alcohol or drugs would have to be involved for a case to become a felony, said former Sonoma County prosecutor Mike Mullins, who was speaking generally and isn't familiar with the Dunaway case.

"The penal code is drafted to distinguish between vehicular manslaughter as the result of using alcohol and drugs, those are felony cases, and all other vehicular manslaughters, which are misdemeanors," said Mullins, who recently retired from the Solano County District Attorney's office.

Prosecutors on Monday met with Ling Murray's husband, Jeff Murray, and Andres, her step-father-in-law, prior to announcing the charge against Dunaway.

Ling Murray was recovering from a recent surgery in her right arm, Andres said. Doctors removed several screws and a plate and she was expected to regain some movement at the elbow over time. Ling Murray continues her recovery at home with physical therapy sessions and a personal trainer.

The mother wasn't ready to face the driver, Andres said, but Jeff Murray and Andres will attend Thursday's hearing.

"I'm certain there will be emotions," Andres said.

Dunaway is set to finish her first year at SSU as classes come to a close Friday, school officials said. Dunaway, who was a star athlete at Petaluma High School, is a member of the university's volleyball team.

Efforts to reach Dunaway on Monday were not successful.