Santa Rosa teen driver in fatal crash to undergo mental health evaluation

A Sonoma County judge ordered a mental competency evaluation for a teen driver who lost control of a vehicle and crashed in east Santa Rosa, killing a friend in the passenger seat, Sonoma County District Attorney officials said Thursday.

Rebecca Guillory, 19, was charged Wednesday with felony vehicular manslaughter and driving with a suspended license in the Sunday night crash that killed her passenger and friend, 18-year-old Michajla Bailey Kostecka of Santa Rosa.

Police suspect Guillory had been drinking alcohol and using drugs before the 11 p.m. collision on winding Mountain Hawk Drive in east Santa Rosa.

Her driver’s license was suspended at the time because of a recent drunken driving arrest in Oakland, Assistant District Attorney William Brockley said.

On Halloween, Guillory was pulled over in Oakland for speeding 92 mph down a street with a 55 or 65 mph limit, Brockley said.

She resisted arrest and it was determined she had a blood alcohol level of 0.029 percent, less than the 0.08 level legally allowed for drivers but more than the 0.01 percent allowed for minors, according to prosecutors.

The similarity in driving behavior between the two incidents indicated she may put the public at risk, Brockley said.

Prosecutors asked for Guillory’s bail to be increased. Judge Robert LaForge agreed to increase bail from $100,000 to $250,000.

Public defender Karen Thompson requested Guillory undergo a mental health evaluation to determine whether she is capable of assisting in her defense. LaForge granted the request.

Guillory returns to court Jan. 9 to possibly enter a plea.

Firefighters freed Guillory from the wrecked Chevrolet Cavalier, which had smashed into a sycamore tree on Mountain Hawk Drive just south of Barn Owl Place.

Kostecka, a recent Elsie Allen High School student, was killed when the two-door car skidded off the road and its passenger side slammed into a tree, police said.

The impact spun the car around, and the driver’s side then smashed into another tree.

Guillory was treated for minor injuries before being booked into the Sonoma County Jail.

Santa Rosa Police Sgt. Summer Black said they haven’t yet established an estimate of how fast Guillory was driving down the 25 mph street.

Officers are using a 3-D simulator to re-create the scene and the dynamics of the crash.

Investigators sent blood samples to a state Department of Justice laboratory to determine whether she was intoxicated.

Witnesses who tried to help Guillory as she was trapped in the car said they smelled alcohol, according to police.

Guillory and Kostecka had been housesitting at a residence further up the hill, a family member said.

You can reach Staff Writer Julie Johnson at 707-521-5220 or On Twitter @jjpressdem.

UPDATED: Please read and follow our commenting policy:

  • This is a family newspaper, please use a kind and respectful tone.
  • No profanity, hate speech or personal attacks. No off-topic remarks.
  • No disinformation about current events.
  • We will remove any comments — or commenters — that do not follow this commenting policy.
Send a letter to the editor

Our Network

The Press Democrat
Sonoma Index-Tribune
Petaluma Argus Courier
North Bay Business Journal
Sonoma Magazine
Bite Club Eats
La Prensa Sonoma
Sonoma County Gazette