Moncks Corner — Cold and calculated. That’s how witnesses described the actions of Roger Anthony Williams after the death of his 2-year-old son, Rodricus, in 2010.

Williams wiped his son with peroxide before he stuffed his lifeless body into a trash can of cement, according to testimony Tuesday in Berkeley County Circuit Court. He was wiping away his fingerprints, according to Williams’ former girlfriend, Grace Trotman, who testified before the jury.

It was the final act of a heartless father who couldn’t summon love for his own son, a man who treated the toddler like a punching bag, an object of scorn, Trotman said. Even his passing failed to stir Williams, she said.

“He said he didn’t know how to feel because he had no feelings for him,” she said about Williams.

Trotman testified during the second day of Williams’ trial on a charge of homicide by child abuse. She detailed how the pair’s plan to cover up the toddler’s death unraveled on July 6, 2010.

Trotman, one of the key witnesses in the case, wore a striped jail uniform. She’s been incarcerated for more than two years for her involvement in the child’s death. She pleaded guilty Feb. 16 to homicide by child abuse and desecration of human remains.

Trotman had signed a plea agreement with prosecutors in which they agreed to drop a charge of unlawful conduct toward a child in exchange for her guilty plea on the other two charges.

Trotman also agreed to cooperate with authorities in exchange for a 20-year sentence on each remaining charge, to be served concurrently. She’ll be sentenced after Williams’ trial.

Trotman took the stand and described what life with Roger Williams was like when they were a couple — fear, abuse and pain. Trotman told a jury she became pregnant and he beat her during the pregnancy.

The pair were living together in 2010 on Longbourne Way in Summerville when Rodricus, whom Williams had with another woman, would visit them. The toddler spent that summer with the couple while the boy’s mother, Shaneka Washington, worked in Columbia. He was supposed to return to his mother by August 2010.

During Rodricus’ stay, his father became violent with him, according to Trotman, who claimed he would hit the toddler when he would “stand like a girl.”

Williams would get Trotman’s daughter to hit Rodricus — both 2 at the time — to “toughen him up,” Trotman testified. The abuse by Williams continued, she said, and the boy began acting differently and suffered two seizures.

The boy’s maternal grandmother, Colette, walked out of the courtroom in tears while hearing Trotman describe the abuse of her grandson by his father. Shaneka Washington lowered her head and sobbed.

On June 7, 2010, Trotman’s daughter and Rodricus were fighting at the home, so Trotman “popped him” and he lost his balance, hitting his head on the wall, Trotman testified.

“He started acting different,” she said. “He was gasping for air. I laid him down and did CPR.”

Trotman told the jury she called Williams, who was at work, and he instructed her not to call 911. Williams’ demeanor appeared normal to his boss after the phone call and he continued to work until his shift was over, about 20 minutes after the call, according to testimony.

Trotman left the boy on the couch while she waited for Williams outside the house, she said. When he returned home from work, the boy was dead, according to Trotman.

Williams left and returned to the home with a trash can and cement that he put in the garage, she testified. He wrapped the body in trash bags and tape after wiping him with peroxide, according to Trotman, then stuffed him in the trash can and covered him with the cement.

The couple rented a truck and traveled toward Orangeburg, where Williams rolled the trash can off the truck and left it behind a trailer, she testified.

About a month later, Washington wanted her son earlier than expected. Williams told Trotman they would need to concoct a story about the boy going missing, Trotman testified.

On July 6, 2010, Trotman went to The Battery in downtown Charleston, where she claimed she was instructed by Williams to meet the boy’s mother. Williams even played a cellphone video recording of the child’s voice in the background, while Trotman spoke to Washington on their way to meet.

The plan was to pretend to lose Rodricus while waiting for Washington, Trotman said. Just like they had discussed, Trotman called 911 and reported him missing. She lied to police, and investigators conducted a massive search for the child.

It appeared Williams turned the tables on Trotman when she used a detective’s phone to call him during the search for the toddler, according to testimony.

“He (Williams) said ‘You better help find my son,’ ” Trotman said. “I was confused because I already knew where he was. It’s like he flipped the whole thing around, like trying to blame everything on me.”

During her next interview with investigators, Trotman led investigators to the boy’s body.

During cross-examination of Trotman, Williams’ defense attorney, James Falk, questioned whether she was jealous of Rodricus’ mother, Washington. Trotman denied it.

Falk indicated to the judge he would be calling Trotman back to the stand later this week.

Williams faces 30 years to life, if convicted.