SEAN GRADY swooned when he laid eyes on the Craigslist ad for a black 1991 Nissan 300ZX.

His parents, Michael and Elsa, didn't want their then-17-year-old son to get ripped off, so they went with him in September 2010 to meet Jamie Campbell, who had posted the ad.

"He seemed like a really nice guy. He seemed trustworthy," Michael Grady said recently. "He didn't seem like a shady character to me."

After a test drive, Campbell - a Radnor Township police sergeant - agreed to sell the car to Sean Grady for $7,500, according to a copy of the sales agreement obtained by the Daily News.

Neither the Warminster teen nor his parents knew that they were about to be scammed by a burly cop who did not even own the car and who had ties to a reputed leader of a Delaware County mob gambling ring - or that the ordeal would end in a tragedy.

Grady plunked down $3,200 up front for the Nissan and another $2,800 he earned through landscaping work over the next few months, copies of Grady's checks show.

But Grady never got the car.

Campbell, 39, led on the teen and his parents for two years by hiding behind layers of lies about a phantom divorce and phony military leave, according to copies of text messages and law-enforcement records obtained by the Daily News.

Sean Grady ultimately told Campbell's bosses in Radnor Township about the scam, and got his money back, his father said. He used the cash to buy a motorcycle.

On Aug. 12, Grady, 19, was killed when, authorities said, his motorcycle collided in Warminster with a car driven by an 18-year-old allegedly under the influence.

Campbell was fired for conduct unbecoming an officer in June, but had an arbitration hearing last week in a bid to get his job back.

A spokeswoman for the Delaware County District Attorney's Office said an investigation into the case was ongoing.

"There are two sides to every story," said Robert DeLuca, Campbell's attorney.

DeLuca said the case was actually a "contractual dispute" that stemmed from the fact that Grady had failed to live up to an agreement to pay off the Nissan in 90 days.

The dispute, DeLuca said, was ultimately settled.

DeLuca declined to address any of the apparent lies that Campbell fed to Grady and his parents, but said he believed Campbell would get his job back.

Michael and Elsa Grady, meanwhile, are left with a gaping hole in their lives, their hearts, their home. They would have celebrated their son's 20th birthday three days after Christmas.

They want to make sure that people know about the fast one that Campbell pulled on their boy, about the mind games he played on the family for years.

"I believe in fighting for what is right. It empowers you," Elsa Grady said, tearfully eyeing pictures of her son splayed across her dining room table.

"Sean would want me to do this because he couldn't believe it, that you couldn't even trust the police."

Suspicions didn't pop up immediately.

Elsa Grady, 45, said she searched the Internet for information on Campbell after her son agreed to buy the Nissan, and his story checked out. He was indeed a cop, and a bear of a man who sometimes dabbled as an amateur boxer.

"He's a police officer, so you think there's really no reason for alarm," said Michael Grady, 50.

The parents later learned that a $600 check that their son wrote to Campbell on Oct. 13, 2010, ended up in the bank account of Nicholas "Nicky the Hat" Cimino, a copy of the check shows.

Cimino pleaded guilty in 2009 to gambling and money-laundering charges after the state Attorney General's Office identified him as the reputed leader of a Delaware County bookmaking operation with mob ties.

In a June 5 interview with Radnor Township officials, Campbell said that he and Cimino grew up together and sometimes watched Pay-Per-View fights, but Campbell maintained that he was unaware of Cimino's criminal past, according to a transcript.

Campbell said that he didn't have a checking or savings account of his own and that Cimino cashed the check so Campbell could give the money to his brother.

"This is not nefarious," said Stephen Patrizio, Cimino's attorney. "It has nothing to do with gambling, and nothing to do with anything that Mr. Cimino has pled guilty to in the past."

Cimino testified at Campbell's arbitration hearing last week. DeLuca said the fact that Cimino had cashed a check for Campbell was "really irrelevant."

The Gradys said they were unaware of Campbell's connection to Cimino, but they were worried by the response their son got on March 11, 2011, when the teen texted the cop to say he was ready to pay the final installment on the Nissan and ride off with the car.

"I have my divorce hearing Friday April 1st. Can not do meeting till then. Car is in her name in my garage. Attorneys will not release nothing till the hearing," Campbell wrote, according to copies of the text messages obtained by the People Paper.

Campbell had never mentioned that he was going through a divorce, Elsa Grady said.

During the next two months, Sean Grady sent texts to Campbell, pleading for some sense of what was happening. Campbell would promise to call - and wouldn't.

"This is getting a bit shady," Sean Grady texted Campbell on May 18.

Campbell wrote back: "Shady? I'm away Military till Fri. Lawyers will have a date by end of week 4 me. I will not stiff U I'm not that kind of person."

On Sept. 11, 2011 - a year after Campbell had agreed to sell the Nissan to Sean Grady - the Warminster teen texted the cop to ask for his $6,000 back.

Campbell texted back, saying that his wife had filed a protection-from-abuse order against him because he had harassed her about the Nissan.

Michael Grady said his son "felt bad for Jamie. He had great compassion. He really thought he was going through a rough time."

Radnor Township officials asked Campbell during his June 5 interview if he had been married or had served in the military.

Campbell's responses to the questions were identical, according to the transcript: "No, I have not."

Campbell continued the text-message merry-go-round as the calendar turned to 2012.

The teen was routinely met with silence as he pressed Campbell for details on the Nissan.

In February, Campbell texted Grady that he would pay the teen $500 by "the end of each month."

Grady ended up receiving two money orders worth $800 total, Elsa Grady said.

Both she and her son met separately with Radnor Township police officials not long after the second money order arrived, and described the ordeal.

Campbell was fired June 18.

Elsa Grady said her son got the rest of his money back from DeLuca, Campbell's attorney. DeLuca said Grady signed a release, indicating that the matter had been settled.

Soon after, the teen bought a motorcycle.

"We weren't happy about it," she said, "but he did a lot of research about safety. He's a good kid, so why shouldn't he be able to have it?"

On Aug. 12, Sean Grady was on his way home from church when his motorcycle collided in Warminster with a sedan driven by Aaron Matthews, 18, of Southampton.

Gone from Grady's family lives was the bright-eyed, kindhearted kid who regularly filled their house with the sound of his fingers dancing across piano keys, who planned to start a heating and air-conditioning business with his older brother.

Matthews was charged this month with driving under the influence, possessing a controlled substance with the intent to deliver and related offenses.

"I don't know if [Campbell] knows what happened to Sean," Elsa Grady said. "I think his heart is so hardened that he wouldn't even care."

So whatever happened to the sleek Nissan for which Sean Grady forked over $6,000?

Campbell told Radnor Township officials that the car was a "dilapidated" and "abandoned" hunk of junk that he gave to his brother, Tom, to help him through a divorce.

Campbell said that his brother was the one who was actually selling the Nissan, but he never thought to say as much to Sean Grady because he "didn't think it was that relevant," according to the transcript.

The ex-cop said that he served as the middle man for the sale of the Nissan, and gave Grady's money to his brother, who used the money to fix the car.

In an unexpected twist, Campbell said, his brother then sold the car to someone else.

Rather than disclose this information to Grady, Campbell said, he tried to bide time for his brother to repay the teen.

"I just said that it was me. I am going through a divorce, and I need time, and my brother started paying it back," Campbell said, according to the transcript.

The transcript shows that when the Radnor officials asked Campbell if he had lied to Grady, he said: "I did."

"I think he needs help," Michael Grady said. "I don't wish him bad, but if he has a problem telling the truth, I don't think you need a guy like that who's supposedly protecting people and upholding the law."

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