Investigators say the suspect crafted an elaborate story about how his son's mother just walked off. They say he even went on the Dr. Phil show to talk about her disappearance. But on Sunday, police say the truth started to unravel.
"Quite frankly in this, had he not confessed we would still be stuck," said Dt. Fil Waters with the Houston Police Department.
The he to whom the detective is referring is Mark Augustin Castellano. He's now charged with the murder of his roommate and 3-year-old son's mother, Michelle Warner. Investigators say Castellano detailed the murder to them step-by-step.
"We had an argument. Couldn't take it anymore. I grabbed her around the throat, pushed her on to the bed, and I hear her neck snap," Det. Waters said Castellano told them.
Investigators say Castellano, 37, tried convincing his family and others that Warner had just walked off two weeks ago. He took their child to Odessa with his family. Last week, Warner's loved ones told police Castellano's story didn't add up. They reported her missing and even launched a search party.
"He knew that he needed to get it (the body) out of the apartment. In the course of the interview, he made the comment to me that I thought about just leaving it there and letting y'all find it," Det. Waters said.
Investigators say Castellano returned to Houston and stuffed Warner's body in a utility container, then dumped the mother of two in an oilfield back in the Midland area. The detective told us the couple's 3-year-old son Cayden was home during the murder. We asked if the little boy witnessed his mom's death...
"Cayden had walked around the corner and looked into the room, and saw Michelle's feet hanging off the bed, and he explained that to Cayden as mommy's asleep," said Det. Waters.
Just to put things into perspective, the drive from Houston to Odessa is about eight hours. Detectives say Castellano told them he kept Warner's body in that container in the back seat of the car for a day and a half before he buried her.
There are new developments in the case of a murdered Houston mom whose body was found in West Texas. Authorities have officially charged the victim's ex-boyfriend with her murder.
Police say Mark Augustin Castellano killed Michelle Warner, then drove her body to Odessa and dumped it.
Warner had been missing for over a week until her body was found on Sunday.
Castellano, 37, is charged with murder. He's being processed and booked into the Harris County Jail. Castellano's first court appearance will happen sometime in the next 24 hours.
He is accused of killing his estranged girlfriend, 31-year-old Michelle Warner, who is also the mother of their three-year-old son, Cayden.
"I know she would never leave her son," said one of Warner's friends.
Warner vanished on September 22. Her friends and family launched a search for her after she didn't show up to her new paralegal job.
"Her phone has been going to voicemail since at least 4. It never came back on. Still goes straight to voicemail," friend Stefanie Helton told Eyewitness News on September 27.
Homicide detectives are revealing the gritty details of the plot. They say Castellano told them he strangled Warner to death at their apartment on September 22, left her body behind, and drove to Odessa to drop off their son with his grandparents.
Police say Castellano then told them he drove back to southwest Houston, put Warner's body in a container then drove with it in the backseat back to Odessa. Castellano told police he dumped her body in a ditch near Midland after letting it sit in the car overnight.
According to investigators, Castellano told authorities in Midland where Warner's body could be found. Odessa police and FBI agents located her body and Castellano was subsequently charged with murder.
He told detectives he'd had enough of her abuse toward him and their son.
"I thought him to be odd, but if I'd have thought that I would've been telling Michelle you don't need to be around him," said Donna Malone, Warner's mother.
Malone spoke with us over the phone from her East Texas home as we broke the news about the charges against Castellano.
"I think that's appropriate and I hope there's justice for Michelle," said Malone.
Castellano's bond is set at $50,000.
An autopsy on Warner's body is scheduled in Ector County, in the Midland-Odessa area.
Their son Cayden is still with Castellano's relatives in Odessa. Police are unsure what he saw, if anything, in their apartment.
Warner's mother told us they will seek custody of that child.
We spoke with a friend of Warner's who is asking for prayers for the family, especially for Warner's two young children.
Stay with Eyewitness News and abc13.com for the latest details as we continue following this developing story.