A Chicago man was sentenced Friday to nine years in federal prison for helping his cousin and his cousin’s then-girlfriend, Heather Mack, kill her socialite mother at a luxury resort in Indonesia in 2014, PEOPLE confirms.
In a plea agreement, 26-year-old Robert Ryan Justin Bibbs admitted that he gave advice to his cousin, Tommy Schaefer, and Mack about how to kill 62-year-old Sheila von Wiese-Mack, who was bludgeoned to death in her resort suite on Aug. 12, 2014.
According to court documents obtained by PEOPLE, Bibbs and Schaefer exchanged multiple emoji-laced text messages about the slaying in which Bibbs suggested alternative methods for killing Mack’s mother and gave other suggestions.
Bibbs pleaded guilty in December to one count of conspiracy to commit the foreign murder of a U.S. national in U.S. District Court in Chicago.
Prosecutors have said that Bibbs believed he would receive a portion of Mack’s inheritance after her mother’s death.
“Sheila Von Wiese was brutally attacked as she lay in bed,” Assistant U.S. Attorney Joseph Fitzpatrick tells PEOPLE. “Mr. Bibbs advocated for the killing and was a vital contributor to the murder plot.”
At his sentencing, Bibbs claimed he was depressed in 2014, when he got involved. (His attorney did not immediately return a message seeking comment.)
“To this day, I don’t recognize the person in those messages,” he said, according to ABC News. “I never expected them to do something so horrific.”
“A mistake is leaving your keys in the car,” countered Judge Rebecca Pallmeyer. “A mistake is not standing by and encouraging an unjustified murder.”
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Authorities said the murder plan was hatched around July 2014 during a meeting in Bibbs’ Chicago home, before Mack and Schaefer went to Indonesia, according to a plea agreement obtained by PEOPLE.
Bibbs later admitted that he and Schaeffer continued to discuss the plan to kill Mack’s mother.
Around July 24 of that year, Bibbs received a text from Schaefer, stating, “She’s really tryna knock her mom off,” apparently referring to Mack.
Later that day, Schaefer wrote, “we gotta talk,” to which Bibbs replied, “about what.”
Schaefer replied, “Bukko bucks. Yo mind bouta be blown.”
About 10 minutes later, Schaefer sent another text message to Bibbs with the phrase “bang bang,” then an emoji depicting dozens of money bags and the words “we on in a month.”
After Schaefer arrived in Indonesia, he sent Bibbs another series of texts. During one of the exchanges, Schaefer told Bibbs that Mack had failed in her attempts to kill her mother.
“Defendant then provided advice to Schaefer via text message on alternative ways to kill Von Wiese, including by drowning her,” the plea agreement states.
Soon afterwards, Schaefer sent Bibbs another text stating, “She wants me to right now…While she is snoozing.”
Bibbs responded, “Go sit on her face wit a pillow then.”
At one point, Schaefer also asked Bibbs how he should kill her.
“Defendant replied ‘If it’s no camera then,’ followed by an emoji indicating ‘okay,’ by which defendant meant that [Schaefer] should carry out the murder as long as no cameras were present, to mitigate the risk of being observed,” according to the plea agreement.
Prosecutors said that soon after that, Schaefer went into the hotel room that Mack and her mom were sharing and bludgeoned von Wiese-Mack to death. The couple then stuffed her body into a suitcase, placed the luggage in a taxicab and fled the scene.
A taxi driver later found her remains in his trunk.
Schaefer and Mack were arrested the following day at another hotel. Schaefer confessed to the killing during the couple’s trial in 2015, in which they both faced death by firing squad. But he claimed he hit von Viese-Mack only because she threatened to harm the couple’s unborn child — as Mack was pregnant at the time — and tried to strangle him.
Mack has maintained her innocence and her attorney has argued that she hid in a bathroom during the deadly argument. Both were convicted of murder.
He ultimately received an 18-year sentence, and she was sentenced to 10 years in Bali’s notorious Kerobokon prison.
At Bibbs’ sentencing, Wiese-Mack’s youngster sister, Debbi Curran, described the horror of seeing a photo online of the suitcase that still contained the body of her sister.
“I can’t look at a suitcase [now] without thinking of my sister’s half-naked body … in a suitcase,” she said, according to ABC News. “This will haunt me for the rest of my life.”