BRAMPTON, Ont. -- A 10-year-old boy who came to live with his father and stepmother in search of a better life was kept chained to his bed, beaten and starved in the months leading up to his death, prosecutors alleged Monday on the first day of the couple's murder trial.

Autopsy results showed "injuries on top of injuries" and open wounds on Shakeil Boothe's emaciated body, as well as clear signs of infection in his lungs and blood stream, Crown lawyer Kelly Slate told a Toronto-area court.

The boy's death was caused by a combination of blunt-force injuries, malnutrition, pneumonia and other infections, she said in her opening statement.

Shakeil's lifeless body was found on May 27, 2011, in the family's Brampton, Ont., home, court heard. The paramedics who first examined him testified Monday they believe he had been dead for some time.

The boy's father, Garfield Boothe, and stepmother, Nichelle Boothe-Rowe, are charged with second-degree murder.

Garfield Boothe was originally charged with failing to provide the necessities of life but that charge was later upgraded to second-degree murder.

Nichelle Boothe-Rowe was previously facing a manslaughter charge.

Shakeil left his grandmother's care in Jamaica in 2009 to come live with his father "for better opportunities, for a better life," Slate said. His mother lived in the U.S. and hoped he would eventually join her there, she said.

Instead, he was dead within two years of his arrival.

Slate said the boy was an "obviously sick, malnourished child with multiple observable injuries" at the time of his death. A recent violent incident "pushed an already downward declining child over the edge and he died," she said.

"Shakeil did not get to that state overnight."

Boothe and Boothe-Rowe "had an obligation to care for their 10-year-old son once he came to Canada," she said.

"Both did just the opposite of that," she said, adding the boy was "treated with abuse and neglect the last months of his life."

Things changed once the couple had a son of their own -- an infant born in September of 2010, Slate argued.

Neighbours noticed Shakeil, previously viewed as a "happy but shy and quiet boy," wasn't seen playing outside or going to school, she said. They were told he was inside playing video games, she said.

And public health nurses who visited to help Boothe-Rowe with the baby "saw no sign of another child living in the house," Slate said.

It was only after Shakeil's death that Boothe-Rowe told a social worker that the 10-year-old had been pulled from school in January and had been abused, the Crown said.

Boothe-Rowe told Kathleen Williams the boy's father hit him with a belt and had once stomped on his chest because he had ripped a page out of the Bible, Slate said.

The stepmother also told Williams that since leaving school, Shakeil was chained to his bed every day and only freed to use the bathroom or shower or when relatives would visit, the lawyer alleged.

Slate warned the jury, however, that Boothe-Rowe's comments can only be used "for or against her."

The afternoon of May 27, Boothe phoned his father, saying he needed to speak to him in person, court heard.

Burke Boodth said his son complained of trouble with Shakeil, including that the boy had been stealing other children's lunches at school. Boodth said he asked to see his grandson and was taken upstairs.

In the boy's bedroom, "someone was lying on the bed with a sheet, he was covered from head to toe," Boodth testified.

Once the sheet was lifted, "I could see Shakeil's lifeless body," he said. "Something was coming out of his mouth."

"Something cold just ran down my body."

Boodth said he told his son to call 911, and after some hesitation, Boothe agreed to do it.

Paramedics testified Monday they found the boy lying in bed, frigid and stiff and foaming at the mouth, suggesting he had been dead for a while.

Kristy Eastwood told the court Shakeil met their standards for someone who is "obviously dead."

"Once categorized as obviously dead, resuscitation is deemed futile," she said.

Another paramedic, Michael Niffin, said he told Boothe "there was nothing to be done, that his son had been dead for some time."

Niffin said he and a Peel Region constable spoke to Boothe after breaking the news of Shakeil's death. Boothe told them his son had been sick with a cold for a few days, Niffin recalled.

The father said he had received a call at work that morning saying Shakeil was unresponsive, but when he returned home around 8:30 a.m., the boy appeared asleep, Niffin testified.

Boothe then slept until about 3:30 p.m., when he found Shakeil wasn't breathing, the paramedic said.