Derek Daigneault

Derek Joseph Daigneault was born in 1995 and was raised in Kansas. His adult life was marked by a substantial criminal record, with prosecutors describing him as a career criminal whose convictions dated back to his teenage years.

Before the murder of Mandy Rose Reynolds, Daigneault had accumulated nine felony convictions, including aggravated burglary, attempted aggravated robbery, aggravated assault, aggravated battery, criminal discharge of a firearm at a residence, criminal possession of a weapon by a felon, possession of methamphetamine and offences involving fleeing from law enforcement. He had served prison sentences in Kansas for violent offences and was on felony probation when he became involved with Reynolds.

Daigneault was staying with his cousin Mandy Rose Reynolds at her apartment in San Marcos, Texas, after she travelled to Kansas to bring him back to Texas. He had been on felony probation and had an active warrant at the time. He remained at Reynolds' apartment for approximately a month before the murder.

On April 4, 2023, Daigneault shot Reynolds in the head. He then placed her body inside a large plastic storage container and transported it from San Marcos to Robinson, Texas. He used an accelerant to ignite the container and left Reynolds' body burning in a field near a residential subdivision.

Daigneault used a firearm to kill Reynolds before attempting to conceal both her identity and the circumstances of her death through arson. The weapon used was a .380 pistol that had belonged to Reynolds' grandmother and was later recovered from Daigneault's possession after his arrest in Kansas. Firearms examination linked a spent casing recovered from the burned container to the pistol.

The murder was followed by a deliberate disposal and concealment operation. Daigneault purchased a large plastic storage container, shovel and gas can at a Walmart in San Marcos the day before Reynolds' body was discovered. Surveillance footage showed him leaving the store in Reynolds' car with her dog Titan visible inside the vehicle. He subsequently transported the container and body to Robinson, where he set them on fire.

On April 5, 2023, Robinson police responded to a reported fire and found Reynolds' body burning inside the plastic container. Her remains were initially so badly burned that authorities could not immediately identify her.

Titan, Reynolds' white Labradoodle, remained near the location and refused to leave. The following day, animal control officers recovered the dog and discovered that his microchip identified Reynolds as his owner. This gave investigators their first major lead to the identity of the victim and allowed them to begin investigating her disappearance from San Marcos.

Investigators learned that Reynolds' Honda Accord was missing and subsequently tracked the vehicle to Wichita, Kansas. Kansas police attempted to stop the car on April 8. Daigneault fled, leading officers on a high-speed pursuit before crashing the vehicle and escaping on foot. He was later found hiding inside a grocery store and arrested. Police recovered the .380 handgun from the vehicle.

Daigneault was extradited to Texas to face the murder charge. His trial took place in McLennan County in November 2024, with prosecutors presenting evidence from Robinson, San Marcos and Wichita investigators.

Jurors heard evidence concerning the Walmart surveillance footage, the purchase of the storage container and other materials, the stolen vehicle, the firearm and the circumstances surrounding Reynolds' death. Medical evidence established that Reynolds died from a gunshot wound to the head. Investigators also presented evidence that Daigneault had impersonated Reynolds when he called Robinson police using her phone after her body had been discovered.

In November 2024, a McLennan County jury convicted Daigneault of murder and sentenced him to life imprisonment. During the sentencing proceedings, Daigneault continued to accuse members of Reynolds' family of involvement in her death. As he was being taken from the courthouse, he told a reporter, "I guess I'm just a murderer."

Daigneault appealed his conviction, arguing that the evidence was insufficient and that the trial court improperly excluded evidence concerning an alleged alternate perpetrator. On April 9, 2026, the Texas Tenth Court of Appeals rejected both arguments and affirmed the conviction and life sentence.

A definitive motive for Reynolds' murder was not established during the prosecution. Daigneault and Reynolds were cousins, and prosecutors presented evidence concerning his criminal history, his stay at Reynolds' apartment and his subsequent actions, but the trial did not establish a clear explanation for why he decided to kill her. Reynolds' family said she had helped Daigneault by travelling to Kansas to bring him back to Texas, making the circumstances surrounding the murder particularly disturbing.

The case attracted considerable attention because Titan's behaviour helped investigators identify Reynolds after her body had been deliberately burned. The dog was microchipped to Reynolds and remained at the crime scene even after her body was removed. The resulting identification led police to Reynolds' home, her missing vehicle and ultimately Daigneault. Investigators then used surveillance footage, vehicle tracking, firearm evidence and other evidence to build the case against him.

Daigneault's criminal history was also a significant feature of the prosecution. He had been convicted of multiple violent and weapons-related offences before Reynolds' murder and was on felony probation with an active warrant. His 2024 murder conviction was his latest major criminal conviction, and his life sentence was upheld on appeal in 2026.

• McLennan County District Attorney's Office
• Robinson Police Department
• San Marcos Police Department
• Wichita Police Department
• Texas Tenth Court of Appeals
• Texas Department of Public Safety
• KWTX
• Associated Press
• NBC News
• People