According to NBC 5 Dallas-Fort Worth, Sixto Banegas Matute has been found guilty of felony first-degree murder and sentenced to 20 years in prison for killing Jennifer Mendez Olascoaga, a 24-year-old Dallas ISD teacher's aide who vanished in September 2023 and whose remains were later found in a wooded area off I-20 in Mesquite.
The verdict closes out a case that began more than two years ago, as reported by NBC 5 Dallas-Fort Worth. Olascoaga was last seen on Sept. 27, 2023, leaving a mobile home park along Highway 175 in Seagoville at about 8:11 p.m., and her car turned up abandoned the next day on Lawson Road, without her purse or phone, as reported by NBC 5 Dallas-Fort Worth. Her car turned up abandoned the next day on Lawson Road, without her purse or phone, the station reports.
Surveillance Video and a Disturbing Trail of Evidence
The Mesquite Police Department released surveillance video showing Olascoaga at a QuikTrip near Highway 175 and Beltline shortly after 8 p.m. on the night she disappeared, per the station's reporting. Detectives later found a 15-minute call and several text messages exchanged between Olascoaga and Matute around the same time she was at the store, according to detectives' records cited in the report.
About two weeks after she went missing, human hair, bones and a torso were found scattered in a wooded area off IH-20 in Mesquite, per an arrest affidavit referenced in the station's coverage. The remains were discovered on Oct. 12, 2023, during a search of a wooded area near Interstate 20 and Lawson Road, according to the Seagoville Police Department's account relayed by inforney.com. The Dallas Medical Examiner's Office identified the remains as Olascoaga's in November 2023, and her death was ultimately ruled a homicide.
Phone Data and Bullet Fragments Build the Case
Investigators said phone records showed both Olascoaga's and Matute's phones pinged in the same area along I-20 within seconds of each other, according to the arrest affidavit. Both phones then pinged again in the area where the remains were later discovered, and forensic analysis revealed small bullet fragments within the hair recovered from the remains, as noted by NBC 5 Dallas-Fort Worth.
That combination of evidence, the station's reporting notes, provided probable cause to charge Matute with murder. Mesquite Police arrested the 34-year-old Balch Springs resident on Jan. 10, 2024, more than three months after Olascoaga disappeared. He was charged with felony first-degree murder and had remained in jail since his arrest, having served over 1,000 days behind bars as of Oct. 13, the station's report notes.
A Difficult Case for Investigators
Mesquite Police had previously described the investigation into the human remains as a difficult one to piece together, a challenge documented in earlier reporting. The months between the discovery of Olascoaga's remains and Matute's eventual arrest reflected the slow, methodical work of matching phone data, forensic evidence and digital communications to build a criminal case.
With the guilty verdict now returned and the 20-year sentence handed down, the case that began with a missing teacher's aide and ended with remains scattered in a Mesquite wooded area has reached its conclusion in court.
