The mother of the two-year-old New Jersey boy who police say was left to die in the roadway by his suspected shoplifter dad after a car crash is speaking out about her late son and the 'disgusting human being' who was supposed to keep him safe.

Mackenzy Trievel tells NBC Philadelphia she was getting ready to pick up little Qadan at 8pm on Tuesday after his four-day stay with his father, 27-year-old Christopher Kuhn, when she got an urgent call that afternoon instructing her to race to the hospital so she could say goodbye to her boy.

Trievel says at the time, she had no idea that her ex-boyfriend had allegedly taken Qadan to a Walmart near Philadelphia to steal a $228 speakers system, then ran a red light and caused a three-car pileup, which led to the toddler being ejected from his dad’s Jeep because he was not secured in his car seat.

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Mother's rage: Mackenzy Trievel called her ex-boyfriend Christopher Kuhn (right) a 'disgusting human being' after the man allegedly left their 2-year-old son (pictured left) to die in the road

Kuhn ran a red light and collided with two other vehicles, and kept running even after his son was thrown from his gold Jeep (pictured right)

Walk of shame: Police say Kuhn led officers on a foot chase after stepping over his son's body, but was caught (pictured in handcuffs)

According to officials, after the rollover crash, Kuhn saw his dying son in the roadway on Route 13, stepped over his body and tried to flee on foot, but officers arrested him after a brief chase.

Kuhn, of Hamilton, New Jersey, remained in the Bucks County Jail on Thursday on third-degree murder, homicide by vehicle, endangering the welfare of a child and six other counts.

'He's a disgusting human being,' Trievel said of Kuhn. 'He was only worried about himself.'

On Facebook, the grieving mother also hit out at the court system, saying that her concerns about Kuhn and his suspected drug addiction had been brushed aside and he was allowed to share custody of Qadan with her.

‘I want justice for my son,’ she demanded. ‘The judges never listened to me and now look what happened, my sweet handsome baby boy is gone!’

In another heartwrenching post, Trievel expressed her all-consuming pain and longing for her deceased child.

'He saved my life and I wish I could have saved his I would give anything to hold him again,’ she wrote in the hours after Qadan’s death. ‘He was the light to my life and ill never forget all the laughs and smiles we shared.’

Meanwhile, a close friend of Christopher Kuhn's came to his defense, telling the station WPVI that he is 'in his own private hell.'

As part of Trievel and Kuhn's shared custody agreement, the toddler had spent four days with his dad and was supposed to be picked up by his mother at 8pm Tuesday

Parent's worst nightmare: Trievel got a call Tuesday afternoon telling her to race to the hospital so she could say goodbye to her boy

Diana Williams told the channel that the 27-year-old Kuhn has a lot of problems, and that 'he is going to suffer and hold on to this for the rest of his life.'

Tullytown police say Kuhn fled the Walmart located at Levittown Town Center early Tuesday afternoon after taking the Vizio speakers worth $228. The Trentonian reported that he was seen using his son as a human shield while being pursued by security guards.

A witness told police Kuhn was seen covering his license plate with a sweatshirt outside the big-box store as his toddler son climbed into the gold-colored SUV on his own and was not buckled in, reported CBS Philadelphia.

Police say Kuhn, driving with a suspended license, ran a red light and collided with two other vehicles, and kept running even after his son was ejected onto the roadway on Route 13. According to officials, Kuhn stepped over his child's body, briefly looked at him and took off running.

Police officers caught up to Kuhn after a short foot chase. Law enforcement officials pointed out that they were not pursuing the suspect when the three-car crash occurred.

The mortally injured boy was rushed to Lower Bucks Hospital, where he was pronounced dead. Nobody else was hurt in the crash.

Police say Kuhn's son was not in a car seat, even though there was one in the vehicle. As of Thursday afternoon, the toddler has not been officially identified, but posts discovered on the suspect's Facebook account indicate that the boy's name was Qadan Kuhn.

Kuhn's Facebook page is filled with photos showing him spending time with Qadan

The 27-year-old dad (left) allegedly used Qadan as a shield while fleeing from the store, then let the boy climbed into his Jeep without putting him in the car seat

Kuhn, seen with Qadan swimming in a pool, has a history of domestic violence and theft

The father's social media account is filled with picture after picture of Kuhn happily posing with his son: horsing around in a car, playing superhero dress-up, frolicking in a pool.

One image shows the father and son sitting side-by-side on a couch, with a caption at the bottom that reads, 'Best Friends.'

Kuhn is being held on $5million cash bail. He is due back in court for a preliminary hearing next Tuesday.

The 27-year-old has had run-ins with the law prior to this week's tragedy: last year, he was charged with aggravated assault, terroristic threats, endangering the welfare of a child and weapons offenses after he allegedly attacked Qadan's mother and pressed a screwdriver against her neck while she cradled their son, who was nine months old at the time, reported The Trentonian.

In 2015, Kuhn pleaded guilty to theft by deception, resisting arrest and terroristic threats. He was sentenced to a fine and three years of probation.

A year prior, he was arrested on fraud charges for allegedly misusing a credit card belonging to a school district where he worked as a substitute teacher, which ultimately cost him his job.

An aunt of Mackenzy Trievel has launched a GoFundMe page to help her niece with Qadan's funeral expenses. As of Thursday afternoon, the campaign has drawn just under $3,500 in donations, easily surpassing the initial goal of $3,000.