When Tricia Todd went missing in Martin County late this April, her ex-husband Steven Williams was annoyed. The 30-year-old had a long drive ahead of him back to the Air Force base in North Carolina, and Todd was supposed to pick up their 2-year-old daughter but never did.

That’s what he told her family and investigators as they searched for miles and days for the hospice nurse.

A month later, as he led investigators to the place where he dismembered his ex-wife’s body and put her remains in a plastic storage bin filled with acid, he looked down complacently at the still-fresh grave.

"There’s no way it could be back any further?" detective Yesenia Carde asked. "You certain this is it here?"

"This will be it," he said, barely audible, in a video released by the Martin County Sheriff’s Office.

New videos and interviews shed light into the ever-evolving lie Williams told friends, family and authorities that nearly let him get away with murder. But as hundreds searched for Todd, the beloved mother and Air Force veteran, for weeks earlier this year, all signs kept pointing back to Williams as the discrepancies in his story kept appearing.

Williams was sentenced to 35 years in prison Sept. 30 after his attorney presented a plea deal in exchange for leading investigators to Todd’s remains back in May. When authorities took the deal, with the OK from Todd’s family, they did not know Williams has dismembered his high-school sweetheart. At the scene, only her pelvis and part of her upper thighs were discernible, according to reports released this week.

At first, Williams told investigators the story he would repeat without fail for weeks: Todd and Williams’ daughter, Faith, was sick late April 26, so they took the toddler to the emergency room in her car. Once cleared, they returned to his Airbnb and she left.

A little while later, he told investigators, he asked Todd to come back because Faith was fussy and asked for her mother. Todd returned and left once the girl fell asleep around midnight. The next day, he tried calling and texting her to pick up their daughter so he could leave, but she never replied, so he dropped Faith off with the family’s babysitter.

Interviews with family and friends led investigators to believe Williams was suspect No. 1 in her disappearance from the beginning. Friends told of infidelities and money issues during the couple’s 10-year marriage, and Williams’ mother told stories of his anger.

Then came the little deviations from Williams’ story: A neighbor told investigators he saw Williams drive Todd’s car the morning she disappeared and that he asked him for a gas can. Security footage showed Todd’s car go back and forth to her home several times as well. Then, several pieces of grainy surveillance video showed him walking from Todd’s home back to his Airbnb when he said he had been asleep.

Investigators went up to North Carolina to ask Williams why he was driving Todd’s car and why he turned around before making it to her home. Well, Williams explained, she had asked him to go get her work computer because she needed to do something important. Then, as he approached the home, he thought it was "stupid" to be doing that and turned around. That’s when he noticed she was out of gas.

Detectives asked Williams if he would come back to Martin County with him, and he agreed.

Once there, Williams walked calmly through the Airbnb where he was staying in April and explained his new story further to detectives: Once he returned from getting gas, he found Todd passed out on the floor. He didn’t know what to do and was worried he would be blamed.

"I didn’t even touch her initially," Williams told detectives when they asked if he checked Todd for vital signs. "All I thought was, ‘This was some kind of trick. This is some kind of ploy to get back at me or to mess things up for me.’ "

He put her body in the car and dumped it somewhere, but he couldn’t remember where.

"Steven, that’s a pretty remarkable moment in your life," Carde said. "Unless you do this every day, you’re going to remember an approximate area."

Investigators pointed to discrepancies on the location of where he said her cellphone was, and mentioned that the phone was shut off at the same time he’s seen on security footage making a U-turn at her home, according to cellphone data.

"What we can’t get past is you continuing to lie about what happened," Detective Daniel Dulac said to Williams as he interviewed him in May. "I need you to tell me the truth about what happened."

Eventually, Williams admitted to an "accident" and him "freaking out" during the early hours of April 27. He cried to Dulac, said he didn’t mean to hurt Todd — that he just pushed her when she got in his face, yelling at him about "stupid stuff" like child support, and she hit her head. She never got up, he said.

"I tried to always do right by her. No matter what the situation," Williams said in between tears. "I just tried to do the right thing."

At some point during the interviews, Williams asked for a lawyer, and before investigators ever charged him in Todd’s death, he came to them with a plea deal: second-degree murder and a 35-year sentence in exchange for bringing them to Todd’s remains.

After authorities agreed to the plea, the drive out to the Hungryland Wildlife and Environmental Area along the border of Martin and Palm Beach counties was silent. Williams sat in his red jumpsuit, staring straight ahead. As he led investigators to the shallow grave, all that could be heard was the squish of the wet ground below him and the chains clamoring around his feet.

After Williams’ sentencing in September, detective Michael Oliver told The Palm Beach Post he went to the Orlando prison to speak with Williams to get the last bit of truth they didn’t have: How and why did Williams kill Todd?

As he sat in front of them, Williams was different: Very chatty, laughing as he described in detail how he killed Todd: He beat her over the head to stop her from screaming and then strangled her, until "her heart stopped beating."

"He didn’t show any remorse," Oliver said.

Why? Williams was tired of Todd disrespecting him.

"Do I believe it? Yes," Oliver said of Williams answers after having him lie to him for months. "For someone who thinks the way he does, yes."