The 2019 killing followed a crash near the Thunderbird Road off-ramp.
PEORIA, Ariz. — A man accused in a deadly freeway attack that followed a Loop 101 crash has admitted guilt in Maricopa County, resolving the central charges in the 2019 killing of Martha Thy.
Fernando Acosta, 32, entered guilty pleas to first-degree murder, kidnapping, aggravated assault and drug possession. The plea covers charges from a violent roadside scene that unfolded in front of passing drivers. Acosta is scheduled to be sentenced July 13, more than seven years after the crash and killing.
The attack happened about 7 a.m. March 22, 2019, after a Lexus went off northbound Loop 101 in Peoria near Thunderbird Road and crashed into a fence. Authorities said Acosta was behind the wheel and Thy was in the passenger seat. Court and police records said Acosta attacked Thy with a knife after the crash, first while she was still in the vehicle and then after she tried to crawl away.
Thy, a Spring Valley, California, woman, was taken to a hospital and died from her injuries. Investigators said she had numerous stab and cut wounds. The attack caused a long freeway closure as troopers secured the scene, interviewed witnesses and documented evidence near the damaged car. Officials have not released a clear public explanation for why the attack began.
Bystanders played a central role before officers arrived. Witness Gustavo Munoz said people stopped their vehicles after seeing the crash and then realized a woman was being attacked. One person fired shots into the ground to try to stop the stabbing, while others moved in, tackled Acosta and held him down. Trooper Kameron Lee later described the scene as loud and confusing, with people running and shouting as officers arrived.
The case moved slowly through the court system before the guilty plea. Acosta was initially held on a high cash bond after prosecutors described the attack in court. The plea avoids a trial and leaves sentencing as the next step. A judge will decide the sentence after reviewing the plea terms, the charges and any statements allowed in court.
Family members previously identified Thy as a mother of three. Her death drew attention in Arizona and Southern California because of the public nature of the attack and the efforts of strangers who tried to stop it. The case also became part of a broader record of domestic violence-related killings investigated on Arizona roadways and in public spaces.
Acosta’s guilty plea marks the first final admission of criminal responsibility in the case. The July 13 sentencing hearing will determine how long he remains in prison and formally close the trial phase of the prosecution.
Author note: Last updated May 30, 2026.