Andrew Sumner spent several hours Wednesday explaining to jurors in Devin Baham’s second-degree murder trial in St. Tammany Parish what happened on Feb. 22, 2012, when Ashley King was stabbed to death in her Slidell apartment and her body later was burned to try to cover up the crime.

On Thursday, Sumner faced repeated challenges from Baham’s attorney, Martin Regan, about whether he was lying to lessen his own punishment or that of his wife, Katelyn Lusich, who also testified Thursday.

Sumner said Wednesday that he and Baham went to the 32-year-old King’s apartment on the afternoon of Feb. 22 to rob her of drugs and money. King had sold pills to Sumner before, and he was known to her. Lusich was to stay in the car and act as a lookout, he said.

Once inside the apartment, Sumner said, Baham attacked King, first punching her and then grabbing her from behind before the pair fell to the ground while Sumner cowered in the kitchen in a panic.

King was stabbed 13 times, at least four of which were severe enough to be fatal, according to the pathologist who did the autopsy on her.

On Thursday, Regan repeatedly asked Sumner about the deal he was offered by prosecutors in exchange for his testimony.

In March, Sumner pleaded guilty to manslaughter, aggravated arson and obstruction of justice. He said that as part of the deal, he was told his sentences could run concurrently, instead of consecutively, reducing his possible jail time from 100 years to 40 years.

“You were looking for a deal from the start?” Regan asked.

“Yes,” Sumner answered. “I knew what I did was wrong.”

Regan pounced on that response, asking Sumner why it took him three years to agree to a deal, and whether he had really been trying to work out a way to get himself and Lusich — who was seven months pregnant with his child at the time of the killing and later became his wife — lesser sentences.

Regan also hammered Sumner on statements he made to Slidell detectives in the days after the crime, when he disclaimed any responsibility for King’s death and lied to detectives about what he knew.

“Your statement to police was full of lies?” Regan asked.

“Yes, sir,” Sumner answered.

Later, in response to questions from prosecutor Julie Knight, Sumner said he had been lying not just to help his own cause but for “all our sakes,” referring to Lusich and Baham.

Regan also asked Sumner if his deal with prosecutors hinged on the outcome of Baham’s trial.

“If you say Devin wasn’t there, you might not get the deal,” he said to Sumner.

To say that would not be the truth, Sumner replied.

Regan also wondered about the several months Sumner and Lusich spent together after both had been freed on bond. During that period, they got married, and Regan asked if they had discussed the case with each other.

“We didn’t talk about the plea deal at any time,” Sumner said.

Thursday afternoon, however, with Lusich on the stand, Regan again returned to this question, and she had a different response.

“How many times, out on bond, did y’all talk about your cases?” he asked the now 20-year-old Lusich.

“More times than I could count,” she replied.

Earlier, under direct examination, Lusich testified that she only learned what Sumner and Baham planned to do on the way to King’s apartment, and that she was “terrified.”

But her terror did not stop her from heeding Sumner’s wishes and washing his and her clothes soon after the two of them returned from King’s apartment, at a time when prosecutors say Baham was still at the apartment.

She also mopped the floor in a recreation room at the house and put money Sumner had stolen from King in a safe, she testified.

Early the next morning, Sumner and Baham told her they had taken care of the situation and that everything would work out, she testified. She also said they told her that if the police came, she should tell them she had been at home all day and that Baham and Sumner had gone to the park to play football.

Then, Sumner and Baham went to a store and bought cleaning supplies to clean Lusich’s car, which the group had driven to King’s, she testified.

The cover-up began to unravel later that evening when a detective showed up to talk to Sumner, she said. After Sumner had been taken to the police station for questioning, Lusich received a text from him telling her to “clean the blue room,” a code that the pair had devised that led her to take the Oxycontin pills Sumner had taken during the robbery and flush them down the toilet.

That night, a detective showed up and asked her to come to the police station, which she did. She first told police the story about staying home while Sumner and Baham went to the park. But hours later, she said, she reversed herself and told the truth.

She had a change of heart because she wanted “justice for the King family,” she said.

As he did with Sumner, Regan quizzed Lusich on the deal she struck in exchange for her testimony. She pleaded guilty in September to obstruction of justice and was sentenced to 40 years. But with time off for good behavior, she said, she might serve as few as 15 years.

“You weren’t going to do this until your attorney negotiated this deal, right?” Regan asked.

“Testifying was always going to happen,” Lusich answered.

The trial is expected to continue Friday.

Follow Faimon A. Roberts III on Twitter, @faimon.