When 27-year-old Mario Juan Chacon stood in a Midland, Texas, courtroom and admitted killing his ex-girlfriend, 20-year-old Madeline Pantoja, he closed one chapter of a case built on phone records, surveillance footage, and a timeline detectives repeatedly said did not add up.
TLDR
Texas defendant Mario Juan Chacon pleaded guilty to murdering ex-girlfriend Madeline Pantoja in Midland, receiving 35 years for murder and 20 for evidence tampering, concurrent, after investigators used surveillance video and phone data to undermine his shifting account of her 2023 disappearance.
According to the Midland County District Attorney’s Office, Chacon pleaded guilty to murder and tampering with evidence in connection with Pantoja’s May 2023 death. Judge David G. Rogers of the 142nd District Court sentenced him to 35 years for murder and 20 years for tampering, to run at the same time, meaning his maximum term is 35 years in state prison.
Disappearance and Early Red Flags
Pantoja was last heard from on the night of May 10th, 2023, after telling a friend she planned to go swimming at their Midland apartment complex the next day. When she stopped answering calls, friends went to her unit at the Palladium Museum Place Apartments but got no response, according to an arrest affidavit described by KWES in Odessa.
On May 11th, 2023, Midland Police Department officers performed a welfare check requested by Pantoja’s brother, again finding no answer at the door. The next day, officers entered the apartment after a caller reported hearing a woman’s voice inside. Court records cited by local media say officers found a mop and a bucket of dirty water near the front door, and the floor was described in the affidavit as “extremely sticky, as it is when too much cleaning product is used when mopping the floor.” The coffee table was missing, the dog had no food or water, the doors were damaged, and a bedsheet bore a large red stain.
Shifting Timeline and Digital Trail
Chacon initially told police he had last seen Pantoja on May 9th, 2023, and had only spoken with her by phone on May 10th while he was at home, according to the affidavit. In a second interview on May 12th, investigators said he changed his account, claiming he met a cousin who lived in the same complex as Pantoja and dropped that cousin off before going home shortly before 11 p.m.
Investigators compared those statements with traffic cameras, private surveillance footage, and cellphone location data. According to the affidavit and reporting by the Midland Reporter-Telegram, video showed Chacon’s pickup truck near the apartment complex just before 2 a.m., and authorities said digital records allowed them to track his movements between 12:26 a.m. and 3:37 a.m., including near South County Road 1160. When detectives interviewed him a third time on May 18th, they told him they had “found lies in his timeline,” and he asked to leave; investigators allowed him to go.
Guilty Plea, Sentencing, and Parole Rules
Two days after that third interview, Texas Rangers used AT&T records to map an area in rural Midland County, where searchers found human remains on May 20th, 2023, near East County Road 190 and South County Road 1138, authorities said. Police confirmed the remains as Pantoja’s based on jewelry. Local media, citing a person close to the investigation, reported that her body had been concealed inside her missing coffee table. Chacon was arrested and charged later that same day.
An autopsy performed in Dallas County concluded that Pantoja died from a combination of strangulation and suffocation and that she had been beaten with hands and at least one object. A Midland County grand jury indicted Chacon for murder on July 19th, 2023, and a separate indictment for tampering with evidence followed on November 19th, 2025. Court records indicate he has remained jailed on $3 million bond since his arrest, and, under his concurrent sentence, he will be transferred to the state prison system, where he will be eligible for parole consideration after serving at least half of his term, with credit for time already spent in pretrial detention.
The case, which began as a missing persons inquiry and a welfare check at a quiet Midland apartment complex, ended with a guilty plea anchored by a digital trail that undercut Chacon’s evolving story. For Pantoja’s family, the conviction and sentence mark a legal conclusion, even as questions remain about how quickly investigators could act when they first confronted discrepancies in the defendant’s account.
