CHICAGO (CBS) — Robert Bibbs knew the text messages would be his undoing from the start.

When the news broke in 2014 that authorities had arrested Heather Mack and Tommy Schaefer for the murder of Chicago socialite Sheila von Wiese-Mack, Bibbs sent another text to someone to say he felt sick over the “possible proof that could lead back to me . . . just texts.”

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More than two years later, Bibbs is set to plead guilty Tuesday to his role in von Wiese-Mack’s murder.

Federal prosecutors charged Bibbs 15 months ago with helping Schaefer and Mack plan the murder of von Wiese-Mack, who was Mack’s mother. The gruesome crime generated international headlines after von Wiese-Mack’s body was discovered in a bloody suitcase. But Bibbs’ role in the plot was not revealed until he was charged in September 2015.

Bibbs, Schaefer’s cousin, is expected to admit his guilt in the Chicago courtroom of U.S. District Judge Rebecca Pallmeyer, court records show. It is not clear to what crime he will plead guilty. Bibbs is charged with conspiracy to kill a person in a foreign country, conspiracy to commit foreign murder of a U.S. national and solicitation of a crime of violence.

The change-of-plea hearing comes seven weeks before what might have been a revealing trial set for Jan. 30. Bibbs is so far the only person charged in the United States in connection with von Wiese-Mack’s August 2014 murder. The suitcase containing von Wiese-Mack’s body was discovered in the trunk of a taxi outside the St. Regis Bali Resort.

Schaefer and Mack have been convicted in Indonesia of killing von Wiese-Mack. Schafer, 23, was sentenced to 18 years in prison for beating von Wiese-Mack to death. Mack, 21, was sentenced to 10 years. The feds say Schaefer expected to put his hands on up to $11 million through Mack’s inheritance. Bibbs also expected to profit, federal prosecutors have alleged.

Sheila von Wiese-Mack (Credit: Caxton Club)

Sheila von Wiese-Mack (Credit: Caxton Club)

Bibbs wore a Nelson Mandela sweatshirt to federal court when he pleaded not guilty to an indictment in October 2015. Meanwhile, a 29-page criminal complaint alleges that, on July 25, 2014, Schaefer texted Bibbs: “She’s really tryna knock her mom off.” About 90 minutes later, Schaefer allegedly texted Bibbs that “we gotta talk” about “Bukko bucks.”

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That’s when the feds suspect Schaefer filled Bibbs in on the plot to murder von Wiese-Mack in the next month.

The feds have said Mack and her mother arrived for a vacation in Bali on Aug. 4, 2014. Bibbs told the feds he knew Mack wanted to attempt her mother’s murder there.

“[Mack] asked me for my advice [on how to kill the victim.],” Bibbs is quoted as saying in the complaint. “So I told her like, ‘If you would ever do something [to kill the victim], don’t get your hands dirty. . . Don’t, don’t like grab a gun and shoot your mom.’”

Authorities have said Schaefer arrived on the island Aug. 12. Mack allegedly told him in a text message they should wait until her mother “passes back out” before trying to kill her.

While waiting, Schaefer allegedly texted Bibbs and said an earlier attempt by Mack to kill her mother by overdose had failed. Bibbs allegedly suggested Schaefer try to drown her in the ocean or “go sit on her face wit a pillow then.”

Eventually, Schaefer texted Bibbs: “This is for you n—a. And the fam. One time. Here I go. Pray for me cuz.” Bibbs replied, “Done. It’s go time.”

After von Wiese-Mack was bludgeoned to death, Schaefer allegedly texted Bibbs: “For some reason I don’t feel bad.” Bibbs texted that von Wiese-Mack “wasn’t a good person,” and “there wasn’t any positive energy released from her body.”

Roughly two minutes later, Bibbs sent another text — a joke about being “overlooked” for the U.S. men’s national basketball team.

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(Source: Sun-Times Media Wire © Chicago Sun-Times 2016. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)