A Texas man will spend decades in prison after admitting he killed his ex-girlfriend and tried to hide what he did.
Mario Juan Chacon, 27, pleaded guilty to murder and tampering with evidence in the 2023 death of 20-year-old Madeline Pantoja. A judge sentenced him to 35 years for murder and 20 years for tampering. The sentences will run at the same time.
The case began on the night of May 10, 2023. That was the last time anyone heard from Pantoja. Friends later told police they had spoken with her that day.
According to an arrest affidavit obtained by Odessa-based NBC affiliate KWES, her final message was to a friend about plans to go swimming at their apartment complex the next day. It sounded normal. No one knew it would be the last time they heard from her.
When Pantoja stopped answering calls, her friends became worried. They went to her unit at the Palladium Museum Place Apartments on West Francis Avenue in Midland. The city sits roughly between Fort Worth and El Paso. They knocked, but no one answered the door.
On May 11, 2023, Pantoja’s brother asked police to do a welfare check. Officers from the Midland Police Department went to the apartment. Again, no one answered, according to court documents obtained by the Midland Reporter-Telegram. There were still no clear signs of what had happened.
The next day, May 12, someone called police and said they had heard a woman’s voice coming from inside the apartment late that morning. This time, officers entered the unit. What they saw raised serious concern.
Near the front door, there was a mop and a bucket filled with dirty water. The floor felt “extremely sticky as it is when too much cleaning product is used when mopping the floor,” according to the arrest affidavit. It looked like someone had tried very hard to clean something up.
Other things were wrong too. Pantoja’s coffee table was missing. Her dog had been left without food or water, something friends said she would never do. There were holes in the bathroom door. A bedroom door had similar damage, and hair was attached to it.
On the bed, the comforter was gone, but the bedsheet had a large red stain that had soaked through the fabric.
By this time, police had already spoken to Chacon once. On May 11, the night before officers entered the apartment, he told them he last saw Pantoja on May 9 and last spoke to her by phone on May 10 while he was at home. But that story did not stay the same.
During a second interview on May 12, Chacon said he forgot to mention that he had met up with a cousin the night Pantoja went missing. The cousin lived in the same apartment complex as Pantoja. Chacon said he dropped his cousin off just before 11 p.m. and then went home.
Investigators checked camera footage from a nearby oil company. It showed Chacon’s pickup truck near the apartment complex just before 2 a.m., hours after he claimed he had left. That discovery raised more questions.
Police used traffic cameras, private surveillance video, and cellphone location data to track Chacon’s movements between 12:26 a.m. and 3:37 a.m. The final camera placed him near South County Road 1160 at 3:22 a.m., according to authorities. His timeline did not match the evidence.
On May 18, 2023, detectives interviewed Chacon a third time. They told him they had “found lies in his timeline.” Chacon responded, “OK,” and asked if he could leave. Investigators allowed him to go at that time.
Two days later, on May 20, police took the next step. Using AT&T records mapped out by Texas Rangers, a search team focused on an area around East County Road 190 and South County Road 1138 in Midland County. The affidavit described it as an “approximate one-mile area.”
During the search, human remains were found. Police confirmed the remains belonged to Pantoja based on jewelry. A source close to the investigation told local media that her body was found inside her missing coffee table. The detail shocked many in the community.
Later that same day, Chacon was arrested and charged.
An autopsy was performed in Dallas County. It revealed that Pantoja died from a combination of strangulation and suffocation. The report said she had also been beaten using hands and at least one object during the attack. The findings showed the violence she endured.
On July 19, 2023, Chacon was formally indicted for murder. More than two years later, on Nov. 19, 2025, he was indicted on the tampering charge as well.
He remained in the Midland County Jail on a $3 million bond after his arrest. In court, the case moved toward its final outcome. Chacon eventually pleaded guilty to both charges.
In quick order, 142nd District Court Judge David G. Rogers sentenced him to 35 years in prison for murder and 20 years for tampering with evidence. The sentences will run concurrently, meaning he will serve them at the same time.
Chacon will soon be transferred to the Texas Department of Corrections. He will become eligible for parole after serving at least half of his sentence. He will also receive credit for the time he has already spent in jail waiting for his case to be resolved.
