Convicted of murdering his business partner, former California businessman Ed Shin is currently sitting in a prison cell, where he’ll live out the rest of his days.

Over a period of six months in 2010, Shin sent emails to his business partner Chris Smith’s immediate family, his girlfriend, friends, even the northern California man’s grandfather. Posing as Smith, Shin told the 31-year-old’s loved ones he had sold his share of the ad company the two founded and was living out his dream traveling the world on a chartered yacht with a Playboy Playmate and a stack of gold coins.

Police say that for about year Shin managed to dupe almost everyone. People believed Shin because Smith was a surfer with wanderlust stitched into his DNA, and he had been investing in gold coins.

Shin, now 42, later confessed to accidentally killing Smith, but he has denied he intentionally murdered him in the office of the company the two men founded.

Former Orange County Senior Deputy District Attorney Matt Murphy, who tried and won the case, insisted Shin is lying.

But the mystery remains: What happened to Smith’s body?

“I can’t talk about that … because I don’t know,” Shin told “20/20.” “There is no way I can get into that at this point … I wish I could tell you more but, there’s something bigger that I just can’t talk about.”

Over the past 14 months, ABC News’ Matt Gutman spent hours visiting Shin in jail, talking with him over a dozen phone calls and exchanged letters with him, trying to understand what motivated this murder and to learn where Smith’s body may be.

Watch the full story on “20/20” FRIDAY, Jan. 24 at 9 p.m. ET on ABC. Subscribe now to “20/20’s” podcast about this case, “Cutthroat Inc.,” debuting on Feb. 27.

Shin and Smith met in Southern California while both were working in companies specializing in lead generation, a form of media advertising that collects customer leads using 800 numbers, and then sells those leads to other companies.

The two men teamed up and later founded their own lead generation company called 800XChange.

But Shin admitted to “20/20” that he was leading a double life. He likened his experience to the movie “Wall Street.”

“That’s all about the money … because you’re making so much money, and then the money’s fast, quick. That’s addicting,” he said.

On one hand, he appeared to be a successful, church-going businessman, married with three kids at home in California. On the other, he was having lavish weekends in Las Vegas, spending the money on women and gambling sprees, and then was secretly siphoning off cash and business from the lead generation company he was working for to the company he and Smith founded.

“The first time I started playing, [I gambled] a couple thousand dollars,” Shin said. “And then, you get good at it. That’s the problem with gambling … most people tend to win early and then you’re addicted to that win.”

By 2009, LG Technologies, a previous lead generation company Shin had been working for in Riverside County, California, discovered what he had done.

Shin pleaded guilty to embezzlement in May 2010 and agreed to pay a total of $800,000 to settle the civil case against him from LG Technologies. Paying that restitution would allow him to avoid prison time, but Shin needed Smith’s sign-off to come up with the funds to satisfy the judgments against him. Adding to the financial pressure Shin was facing, authorities said, was that Shin had also racked up big gambling debts in Las Vegas.

“Ed Shin was in a corner. Chris Smith had him in a corner,” said Murphy, the former senior deputy district attorney and an ABC News contributor. “The way he could solve his problems, financially, business-wise, everything else, is murder Chris Smith, make him disappear and take all of his money.”

Then, in June 2010, Chris Smith abruptly disappeared, apparently on a round-the-world surfing trip. Smith’s family received emails supposedly from Smith saying he was traveling. As weeks turned into months, his family and law enforcement began searching for answers.

By early 2011, Shin’s scheme started to unravel. A computer expert the Smith family brought in to analyze data in Chris’ emails had discovered the messages had all been sent within the U.S., not abroad, and forensic tests performed by investigators at the former 800XChange office space had revealed large presences of blood.

“It was helter-skelter,” Murphy said. “It was a bloody mess.”

Months later, DNA tests confirmed the blood found in their former office belonged to Chris Smith.

Shin was arrested at the Los Angeles International Airport in August 2011 as he was boarding a flight for Canada. At the time, he was still on probation from the embezzlement case, police said.

“We technically arrested him for violating his probation because … he’s not allowed to leave the country,” Sgt. Don Voght told “20/20.”

During his interrogation, Shin claimed at first that the blood discovered in their former office space was from an injury Shin sustained while cutting an apple. But when detectives confronted him with proof that it was Smith’s blood, Shin changed his story. Instead, he told police the two men had engaged in a knock-down-drag-out fight, claiming Smith lunged at him and Shin was forced to defend himself.

Shin insisted that Smith fell and accidentally hit his head on a desk, which caused a fatal injury.

That was the story Shin stuck to when he testified at his murder trial.

Shin also told police, and then testified at trial, that he paid an Eastern European man thousands of dollars to dispose of Smith’s body. He told “20/20” he never even asked for the man’s name.

“What’s the point of knowing?,” he asked “20/20.”

When asked why he didn’t call 911 after the fight, Shin said, “I was in total panic. What are you supposed to do at that point? I was already in a criminal case, the Riverside case… [I thought] ‘Oh my God, I’m in this criminal case. No one’s ever going to believe me. These cops aren’t going to believe me.’”

Shin was convicted in December 2018 of first-degree murder with special circumstances, and was sentenced to life in prison without the possibility of parole. He continues to claim that Chris Smith had died by accident during their fight.

“I wasn’t trying to kill him, but we got in a fight,” Shin told “20/20.”

To this day, Smith’s body has never been found.

Authorities said Smith’s blood was discovered in Smith’s Range Rover, and that cellphone records revealed Shin’s mobile phone had pinged towers in Boulevard, California, a town near the Mexico border nearly 200 miles away, on June 7, 2010, and June 9, 2010 — days after Smith disappeared.

“Ed’s a big enough guy, he can get that body into that car by himself,” Murphy said. “I’ve always believed he drove him out to the desert.”

“There’s no reason for Ed Shin to have driven in the middle of the night and sat there … unless he’s dumping the body of Chris Smith,” added Julia Bowman, a former Laguna Beach detective who helped uncover Shin’s elaborate deception.

Shin claims he was trying to flee to Mexico, not get rid of Smith’s body. When he reached the border he said he told police he “couldn’t go through with it.”

He continues to insist he doesn’t know what happened to Smith’s remains, but admits there’s more to the story.

“You have to think about it,” Shin said. “If someone’s willing to give up his life to protect a secret, there’s a reason.”

ABC News’ Sunny Antrim and Richard O’Regan contributed to this report.