COMING UP ON 48 HOURS MYSTERY: TELEVANGELIST JOYCE MEYER'S FORMER HEAD OF SECURITY FOUND GUILTY IN TRIPLE MURDER "THE WRITING ON THE WALL" SATURDAY, MAY 5 (10:00 PM, ET/PT)

On the morning of May 5, 2009, Christopher Coleman called his neighbor, police detective Justin Barlow, and asked him to check on his wife, Sheri, and their two young sons, Gavin and Garett, after his own calls had gone unanswered. For months, Coleman, head of security for well-known televangelist Joyce Meyer, had been receiving explicit death threats regarding his involvement in Meyer's ministry. What Barlow discovered upon entering the Coleman home through an unlocked basement would send shockwaves through the small town of Columbia, Ill.

Inside the home police found spray-painted messages on the walls, with the phrases "You have paid" and "Punished." Upstairs police discovered the bodies of Sheri, 31, Garett, 11, and Gavin, 9. Police thought the threats and the writing on the wall would be key in discovering who killed Coleman's family.

In their investigation, police discovered that Coleman had been having an affair with one of Sheri's high school friends, Tara Lintz, a Florida cocktail waitress. Lintz told police the two had a mutual obsession with each other had plans to marry after Coleman divorced his wife.

Two weeks after the murders police had enough evidence to charge Coleman. Coleman insisted the murders were committed by whoever had sent him the threats.

"This crime was about greed, sex, selfishness and narcissism," prosecuting attorney Ed Parkinson told 48 HOURS MYSTERY correspondent Maureen Maher. "Chris Coleman decided he wanted a new life [with Lintz] and his family was in the way. He was obviously a monster who carried out a very sadistic plan."

Maher talks with investigators, defense and prosecution attorneys and jurors and Nick Pistor, a reporter who covered the case for three years. Maher also speaks with Christopher Coleman's parents, who refuse to believe that their son committed this crime. Sheri's mother, brother and close friends talk about their journey in getting justice for Sheri, Garett and Gavin.

Jurors on the case tell Maher about a crucial piece of evidence they discovered during deliberations, which they say solidified for them any question of who the killer was.

The primetime broadcast entitled "The Writing on the Wall" will air on Saturday, May 5 (10:00-11:00 PM, ET/PT) on the CBS Television Network.

Follow 48 HOURS MYSTERY on Facebook and Twitter