EL MONTE (CBSLA) — It has been almost three decades since a Southland man walked out of his home for a business meeting and never returned.

Austin Jay Smith, 23, went missing 28 years ago. (CBSLA)

READ MORE: Clippers Lose to Cavaliers 92-79

“Anniversaries, birthdays, the holidays, there’s always one person missing, and so they’re always difficult,” Teddie Smith, the victim’s sister, said. “Our hearts are still sad.”

That sadness became part of the Smith family’s life 28 years ago when Austin Jay Smith went missing.

“His life was good,” Smith said. “There was no reason to just walk out.”

The 23-year-old, who went by Jay, walked out of the El Monte home he shared with his mother on March 23, 1993. The aspiring accountant hasn’t been seen since.

Det. Richard Lopez, of the Los Angeles County Sheriff’s Department’s Cold Case Unit took over Jay’s case in 2013. By that time, the missing person case had turned into a homicide investigation.

According to family members, Jay went to meet his former employer at Rosemead High School around 8:30 p.m. The man, a stage crew manager at the school’s auditorium, told Jay that he could borrow some equipment for the DJ work he did on the side to support his widowed mother.

Jay’s mother and girlfriend at the time said they were concerned about the meeting because he had a strained relationship with his former boss, so his girlfriend drove to the auditorium.

“While she was there, she noticed that Jay’s little 1992 Mazda pick-up truck was parked right next to the former employer’s truck, which had a camper,” Lopez said.

After a while, Jay’s girlfriend knocked on the door of the auditorium to check on him.

“The former employer denied her entrance and actually slammed the door in her face,” Lopez said.

Investigators have photos of both Smith’s white pick-up truck and the vehicle of a suspect in the his disappearance. (CBSLA)

The woman left the school, but when she drove past again — just after 11 p.m. — she noticed that the two vehicles were still there. When Jay didn’t come home, the search began.

Investigators soon learned that another school employee saw Jay’s former boss walking back to the auditorium at about midnight the night of the meeting and offered him a ride. The employee said when the man got in the vehicle, he was disheveled and mumbling.

READ MORE: Beverly Hills Police Department Accused Of Racial Profiling

When they got to the auditorium, the employee said that Jay’s truck was no longer in the parking lot. The truck was found the next night, parked behind a dumpster a few blocks from the high school.

“So that’s pretty damning right there,” Lopez said. “There were three different versions of what the employer said happened to Jay or who Jay left with. He was the last one to see Jay alive.”

Investigators questioned the man, who was now a suspect in Jay’s disappearance, and others to figure out a motive. Detectives found out that Jay had sent a letter to the school board telling them that his former boss was stealing funds from the school by renting out the auditorium and equipment and pocketing the money.

“The former employer had talked to several students that had explained that he knew that it was Jay who turned him in, and that he told one student that if he had a chance, he’d take Jay to an alley and beat him up,” Lopez said.

The detectives searched Jay’s truck, but didn’t find any evidence. They searched the auditorium and found a small amount of blood, but it was accidentally discarded before Lopez took over the case. But what wasn’t found in the auditorium was a large barrel that students used for their theater productions.

“The barrel was missing shortly after Jay went missing,” Lopez said. “Jay’s body could’ve been moved in that barrel.”

Since Smith’s disappearance, detectives have gathered boxes full of evidence including photographs, documents and interviews. (CBSLA)

With all of the information gathered, investigators and the Smith family believe Jay was killed and his former boss was somehow involved.

“He left the scene and was gone for two weeks,” Smith said. “So he had two weeks to take him anywhere and dump him.”

Over the years, detectives compiled extensive evidence including boxes of documents, interviews and photos. Authorities also had a suspect and a probable motive, but it was not enough for prosecutors to file criminal charges because Jay’s body has not yet been found.

According to Lopez, prosecutors in 1993 did not try no-body cases due to the difficulty of a successful conviction.

“You’ll have to answer someday to what you’ve done,” Smith said.

Until an arrest is made, the Smiths know that the man suspected of being involved will continue to live life with his family in the Southland. A request for comment from the man was not immediately returned.

MORE NEWS: Woman Reported Missing In Rowland Heights Found

Anyone with information about the case is asked to call the LASD Homicide Bureau at 323-890-5500.