TAMPA — Testimony began Tuesday in the trial of a Tampa man prosecutors say brutally killed a 34-year-old father and then showed off the victim's body to a group of friends.

Amer Ejak, 20, is charged with first-degree murder in the September 2009 death of Thomas Johannesen. Ejak, who is being prosecuted as an adult, was 16 at the time of Johannesen's death.

In his opening statement, Hillsborough Assistant State Attorney Nicholas Glance described a vicious killing followed by a ghastly show-and-tell. Glance said Ejak clubbed Johannesen — nicknamed "Jim Beam" because of his fondness for liquor — over the head with a bottle of Johannesen's eponymous bourbon.

Prosecutors say Ejak and Christopher Cox then placed a plastic bag over Johannesen's head and strangled him with a belt. The pair tied a red bandanna over Johannesen's mouth as a sign of their gang affiliation, Glance said, and stuffed Johannesen into the closet at his apartment at Oak Ramble apartments, southeast of Bruce B. Downs Boulevard.

After the killing, Glance said, Ejak and Cox "were kind of making inside jokes and singing a song about hitting someone in the head with a bottle," Glance said, and witnesses noticed that Cox had given Ejak a new nickname, "Bing," after the sound the bottle made on the victim's head.

Do you want to see a dead body? the pair allegedly asked two women.

"At some point that day, they all went upstairs" to Johannesen's apartment, Glance said. "They opened the closet, and in the closet, in his own bedroom, was the body of Thomas Johannesen, lying on his back with a belt around his neck."

Johannesen had a son, now 9, with a wife from whom he was separated.

Cox pleaded guilty to second-degree murder last year and is serving a 25-year term in state prison.

Ejak, who has dark hair tied back in a ponytail and wispy sideburns, looked warily around the courtroom as opening statements began. He wore a gray suit, too large for his frame. The collar of his jacket was turned upward until a bailiff suggested he fold it down.

Ejak was ordered incompetent to stand trial last year following a psychological evaluation. Four months later, he was ruled competent and his prosecution proceeded.

Nick Sinardi, Ejak's Tampa-based defense attorney, acknowledged in his opening statement that physical evidence tied his client to the victim's apartment — investigators discovered DNA that matched Ejak's, and the red bandanna tied over Johannesen's mouth belonged to Ejak — and that the death "was no accident."

But Sinardi said the state's evidence falls short of proving beyond a reasonable doubt that Ejak was the killer.

"Mr. Ejak owned that bandanna. We don't dispute that," he said. "But that is not to say that he is the individual who put that bandanna on Mr. Johannesen's face."

Sinardi said it was Cox, not Ejak, who had invited the two women to see a body.

Testimony in the case continues today.

Times news researcher John Martin contributed to this report. Peter Jamison can be reached at pjamison@tampabay.com or (813) 226-3337. Follow him on Twitter @petejamison.