(Updated: October 9, 2010 12:35 p.m.)

CHICAGO (CBS) – Bond was denied Saturday for a Chicago man accused of strangling his toddler son over a domestic dispute with the boy’s mother, who refused to continue a relationship with the father.

Donald Johnson, 30, was charged with first-degree murder on Friday in the death of 14-month old Dontrell Johnson, whose body was pulled from Lake Michigan on Thursday. A Cook County judge denied Johnson bond at a hearing at the Cook County Criminal Courts building Saturday afternoon.

The Cook County’s Medical Examiner’s Office on Friday said Dontrell died by strangulation, and his death was ruled a homicide.

Donald Johnson’s family said they believe he killed his son because of a broken heart. He picked up his son on Monday for a visit and was supposed to return Dontrell to his mother, Regina Quarles on Thursday.

But Wednesday night, Donald Johnson started making disturbing phone calls threatening to kill himself and the baby because Quarles would not come to his home to spend time with him and their son.

Donald Johnson was taken into police custody Wednesday night, but police did not find Dontrell with him and Johnson refused to tell police where the boy was.

Thursday afternoon, Dontrell’s body was spotted by a boater on Lake Michigan. Paramedics tried to revive the boy, but he died a short time later at University of Chicago’s Comer Children’s Hospital.

Donald Johnson’s mother, Sheila Young, said her grandson’s murder has been almost too much for her to and her brother to bear. She last saw her grandson Wednesday morning.

“(He was) just waving, and he lit up like a Christmas tree,” she recalled. “I will never ever forget that. Like my baby knew he was going to heaven, like he knew this was his last day.”

Donald Johnson’s uncle, Jason Stigler, received one of his nephew’s disturbing phone calls that afternoon.

”When he told me the baby is gone, I took it as the baby is dead,” Stigler said.

Sheila Young said that she knew her grandson was dead when police told her that Donald Johnson would not say where the boy was.

“I was like ‘The way he gave you all that love, the way he talked to you and the things he did, how did you kill him Don?’ Because I knew he was dead. I knew he was dead,” she said.

Young said she believes her son also planned to kill himself but didn’t go through with it.

She says a letter found Friday that was written by Johnson and dated Oct. 4 is proof of that plan — and perhaps a motive. In it, her son talked about the love he has for Dontrell’s mother. The two had broken up, but Johnson’s mother said he never got over her.

“He couldn’t have her. He couldn’t be in a relationship with her,” she said. “So, what’s going to hurt her more? The baby. That’s why he done it,” Young said.

The victim’s family rejoiced at the news that Johnson had been charged. They say it’s a great relief and they plan to be at his hearing. They are also planning a prayer vigil for Sunday afternoon near the place where Dontrell’s body was pulled from Lake Michigan.

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