UPDATED 04/25/12 – 9:48 p.m.

ALSIP, Ill. (CBS) — A 5-year-old boy with a serious heart condition is awaiting a reunion with his mother, while the boy’s father, aunt, and grandmother stand charged with kidnapping him from a St. Louis hospital.

Porter Stone remained at Advocate Christ Medical Center in Oak Lawn Wednesday afternoon, waiting for the reunion with his mother.

His mother, Tiffany Stone, arrived at O’Hare International Airport on a flight from St. Louis at about 8:30 p.m. on Wednesday. From there, she planned to go to Advocate Christ to be reunited with Porter, who was resting and playing games on the Wii inside the hospital.

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“I’m just ready to go get my son,” she told reporters while picking up her luggage at O’Hare.

Porter and his mom will head back to Missouri on Thursday.

As CBS 2’s Susanna Song reports, Tuesday night was a scary and stressful night for the family, who was worried about Porter’s health. He had been kidnapped from St. Louis Children’s Hospital, with only about a day’s worth of medication left in a portable IV on him. He suffers from cardiomyopathy, a thickening of the heart muscle that prevents the heart from pumping blood correct.

“He is currently on medicine for his heart condition, which is continuously infused into his vein,” said Dr. F. Sessions Cole, a physician who treats Porter.

Porter had only enough medicine to last 24 hours when he was abducted.

“If that medicine had run out, and he started going into cardiac arrest, there wouldn’t have been any hope for him,” said Porter’s maternal grandfather, Matt Fife.

Porter is, in fact, next on a transplant waiting list to get a new heart. He will be able to go home to St. Joseph until his new heart is ready, then he’ll go back to St. Louis for the transplant.

Police say Porter’s father, Jeffrey Stone, 33; his paternal aunt, Heather Minton, 37; and his paternal grandmother, Rhonda Maria Matthews, 59, abducted him in St. Louis on Tuesday.

Jeffrey Stone, Rhonda Maria Matthews, and Heather Minton (left to right) allegedly kidnapped Stone's 5-year-old son Porter from a hospital in St. Louis and took him to a motel in Alsip, where the three were arrested and Porter was rescued. (Credit: Alsip Police)

Porter’s mother has sole custody of the boy, but is in the middle of a bitter divorce from her estranged husband. But she said she never thought her estranged husband would put porter in the middle.

“I have no idea why he would do that, other than to hurt me,” Tiffany said in a phone interview with CBS 2’s Marissa Bailey. “He knows that … it did hurt me and; and i think that was one of his major motivations.”

CBS St. Louis reports Porter had been discharged from the hospital so he could be closer to his home outside of Kansas City, when he left with his father to get their car together. Jeffrey Stone then reportedly called the boy’s mother, who was still at the hospital, to say he was leaving with the child.

Investigators said Jeffrey Stone called Tiffany repeatedly while on the run, calling her names and refusing to let her speak to her son.

“I wasn’t afraid for my life, but it was just very derogatory, and, you know, it was just very obvious,” she said. “It made his motivation perfectly clear.”

Although she wasn’t afraid for her own life, Tiffany Porter was afraid for her son.

“I knew that he didn’t have his meds, and I didn’t know when I was going to see him again,” she said.

An Amber Alert was issued immediately after the abduction, as doctors feared for Porter’s life. Police are crediting the Amber Alert system with helping to resolve the case. Early Wednesday morning, Illinois State Police arrested Matthews, Minton, and Jeffery Stone at a motel in Alsip, after tracking them down using cell phone GPS technology.

“It’s fantastic,” said Alsip police Lt. Scott Zablotny. “I mean, this is a textbook case of what it’s designed to do.”

Zablotny says an Amber Alert allows for millions of sets of eyes. One of those sets of eyes spotted the car that was carrying Porter, but Zablotny said he could not reveal who tipped police off at this time.

The Amber Alert was flashing on the electronic signs on the Tri-State Tollway. Zablotny said, nine hours after Porter was abducted, the car was found in the Baymont Hotel parking lot, at 12801 S. Cicero Av., in Alsip. Officers broke down the door to the room where Jeffrey Stone had holed up with his mother, sister, and Porter.

Jeffrey Stone, of Texas; and Rhonda Matthews and Heather Minton, both of California, were arrested. They’ve been charged felony counts of kidnapping, endangering a child and interfering with custody of a child. All three are being held on $1 million bond.

Meantime, Porter’s mom got the call that her little boy was safe.

“He was very, very scared,” she said. “He was crying, and it was heartbreaking.”

Porter was not hurt, and was taken to Advocate Christ for a checkup. The good news quickly reached St. Joseph, Mo.

“It just felt like we were in a nightmare that we were never going to get out of,” Jessica Chavez, Porter’s soon-to-be aunt, told KCTV-TV’s Nima Shaffe. “We knew that Jeff had him. We just didn’t know where they were going there were they were going. There were just too many possibilities, and so it was just… none of us has been to sleep, just waiting to hear the news, and we’re beyond ecstatic to hear that he’s OK.”

Added Porter’s maternal grandmother: “We’re hearing that Porter’s doing OK. He’s been taken to a hospital to make sure. We’re going to fly his mother out to Porter to reunite them, and then take him back to the hospital.”