The sentence closes a case that moved from a missing person report to a murder conviction built on digital evidence, search records and autopsy findings.
MIDLAND, Texas — The man accused of killing 20-year-old Madeline Pantoja after she disappeared from her Midland apartment in 2023 has pleaded guilty and been sentenced to prison, bringing a courtroom resolution to a case that gripped the city for months and remained active in court for nearly three years.
Mario Juan Chacon, 27, pleaded guilty Feb. 20 to murder and tampering with evidence in the 142nd District Court. Judge David G. Rogers sentenced him to 35 years in prison on the murder count and 20 years on the tampering charge, with both terms running concurrently. The plea spared prosecutors from trying a case that had already developed into a detailed timeline supported by surveillance video, cellphone records, witness statements and autopsy findings. It also ended a prosecution that began in the tense days after Pantoja stopped answering calls and friends realized something was wrong inside her apartment.
Pantoja was last seen May 10, 2023, at her apartment on West Francis Avenue in south Midland. Friends later told investigators they had been in contact with her that day, and one friend said Pantoja had talked about swimming at the apartment complex pool the next day. When she stopped answering her phone, friends went to check on her, then family members asked police for help. Officers first responded May 11 for a welfare check. No one answered the door. The next day, after another report connected to the apartment, officers entered and found a scene that suggested cleaning efforts and possible violence. Police said there was a mop and dirty water by the front door, an unusually sticky floor as if too much cleaning product had been used, and damage to a bathroom door and a bedroom door. Hair was attached to the damaged bedroom door, the comforter was gone from the bed and a red stain covered part of the bedsheet. Pantoja’s coffee table was also missing, and her dog had been left without food or water.
Investigators quickly focused on Chacon, who had dated Pantoja. Early interviews became a key part of the case because detectives said his timeline did not hold up. He first told police he last saw her May 9 and last spoke with her by phone May 10. Later, he said he had left a cousin at the apartment complex on the night she vanished and then drove home before 11 p.m. Investigators said nearby footage contradicted that account. Court documents described a larger digital trail assembled from traffic cameras, private surveillance systems and cellphone location records. Authorities said those records tracked Chacon between 12:26 a.m. and 3:37 a.m. on the night in question, placing him near the apartment complex in the early hours and later near a remote county road outside Midland. When detectives told him in a May 18 interview that they had found lies in his timeline, he acknowledged them with a brief response and asked to leave. He was not arrested that day.
The break came on May 20, when search teams used records analyzed by Texas Rangers to narrow a rural search area in Midland County. Human remains were discovered that day in an area east of Midland near County Road 190. Police said the remains were identified as Pantoja’s based on jewelry and that a full autopsy would follow in Dallas County. Chacon was arrested that same afternoon and booked on a murder charge. Public reporting later said a source close to the investigation stated Pantoja’s body had been concealed inside her missing coffee table. Investigators did not make that point part of their initial public statement, which instead centered on the recovery of remains and the arrest. Even so, the missing table became one of the most striking elements of the case because officers had already noted its absence during the apartment search, linking the scene inside the home to what searchers later found in the county.
The medical findings were severe. The autopsy concluded that Pantoja died from strangulation and suffocation, and investigators said the fatal assault also involved a beating with hands and at least one object. Those conclusions supported the first-degree murder case and helped prosecutors explain the physical damage and blood evidence reported from the apartment. The search that preceded the arrest had been extensive. Midland police said in May 2023 that officers and partner agencies had searched about 60 square miles of remote land, executed more than a dozen search warrants, interviewed roughly 25 people and followed about 20 tips. The agencies involved included the Midland County Sheriff’s Office, Texas Rangers, the FBI and Homeland Security Investigations. Then Police Chief Seth Herman defended the department’s methodical approach as public worry and frustration grew. City officials said they were in contact with Pantoja’s family while the investigation unfolded.
Once charges were filed, the court process moved more slowly than the first frantic days of the search. Chacon was indicted for murder on July 19, 2023. The tampering charge was added in a later indictment on Nov. 19, 2025. He remained jailed on $3 million bond as the case proceeded. The final outcome came through a guilty plea rather than a jury trial, a common end point in serious criminal cases when prosecutors and defense lawyers decide the evidence and sentencing exposure leave little room for a better result at trial. Rogers ordered the sentences to run together, meaning the longer 35-year term controls the time Chacon faces in prison. He will receive credit for time already spent in jail, and reports on the case said he becomes eligible for parole after serving at least half of that sentence. In Texas, parole eligibility opens the review process but does not guarantee release.
For Midland, the case remained larger than its court file. It was one of those investigations in which ordinary details became markers of fear and memory: a silent phone, a dog left alone, a cleaned floor that looked wrong, a missing piece of furniture and a search field on the edge of town. Pantoja’s family and friends pushed for answers while trying to keep attention on her disappearance in the days before her body was found. By the time Chacon entered his plea, prosecutors no longer had to prove where the case was headed. They only had to finish it. The plea did that without testimony from a full trial, but it also meant many details that might have been laid out in open court will likely remain confined to affidavits, reports and investigative files instead of public witness testimony.
Currently, Chacon awaits transfer from the Midland County Jail into state custody. With the plea and sentencing complete, the next formal milestone is his move into the prison system and any later parole review under Texas law.
Author note: Last updated March 22, 2026.