The jury heard from Jacob Melton, who was friends with one of the Moorer's sons, that Sidney had Tammy's name tattooed on his lower waist when she learned about the extramarital affair, according to the New York Times.
"If you didn't have that thing with that girl, this wouldn't be happening," Tammy allegedly told her husband, according to Melton's testimony.
Tammy's attorneys argued that the Moorers were in an "open marriage" and suggested Tammy wasn't jealous of her husband's relationship with the young woman.
But Dennis Clark, a former manager at the Tilted Kilt — the bar where Sidney performed maintenance work and met Ms Elvis — testified that Tammy demanded on the phone that the hostess be fired or her husband wouldn't continue to do repairs.
"Tammy barged into the conversation and proceeded to tell me how Heather was causing problems for her family, spreading rumours that she was pregnant by her husband and (said) to fire her," Mr Clark told the court.
According to Myrtle Beach Online, Mr Hart said she was a good employee, "so I was not going to fire her".
It was also reported that after the phone conversation, there was a time Heather showed up to work with a black eye.
Prosecutors said it was jealousy that led to the kidnapping of heathers who was last known to be in the Peachtree Landing area of Socastee.
Both Tammy and Sidney have been charged in connection to Ms Elvis's case. The pair initially faced murder and kidnapping allegations in 2014, but two years later the murder charges were dropped, the New York Post reported.
Last year, Sidney was sentenced to 10 years in prison for obstruction of justice.
Prosecutors said he lied during investigators about his contact with the victim the day she disappeared.
The victim's vehicle was later found abandoned at a boat landing.
Elvis' roommate allegedly said Heather told her Sidney had called to say he was leaving his wife so they could be exclusive with one another.
Cell phone records show the last contact between Heather and Sidney was at 6am on the day she disappeared.
A December 19 police report, made on the day her car was found, included a statement from Sidney admitting he had been in contact with the girl, to tell her to "quit calling him and that was it," The Daily Mail reported.
Elvis had reportedly been on a date on the night she disappeared. He had dropped her off at the apartment at about 2am, but he has been ruled out of the investigation, a source told Fox News.