'Suitcase killer' Heather Mack was arrested by the FBI after returning from Bali and charged with conspiring to kill her mother

• "Suitcase killer" Heather Mack was arrested by the FBI on Wednesday at Chicago O'Hare Intl. airport.
• An unsealed 2017 indictment charges Mack and her then-partner with conspiring to kill her mother.

'"Suitcase killer" Heather Mack was arrested by the FBI at Chicago O'Hare International airport on Wednesday on conspiracy charges. She was deported from a Bali prison where she served time after Indonesian authorities charged her with killing her mother with the help of her then-boyfriend Tommy Schaefer.

An indictment that was unsealed by the US Department of Justice on Wednesday revealed that Mack and Schaefer were indicted in 2017 on charges of conspiring to kill Sheila von Wiese-Mack, Mack's mother on August 12, 2014.

Mack and Schaefer were indicted on one count of conspiracy to kill in a foreign country and one count of conspiracy to commit foreign murder of a US national, as well as one count of obstruction of justice.

Mack was returning from serving part of a 10-year sentence in an Indonesian prison but was released after seven years and two months for "good behavior," according to the Chicago Sun-Times.

Mack and Schaefer were initially arrested by Indonesian authorities during a trip to Bali in 2014, a day after the body of Sheila von Wiese-Mack was found in a suitcase inside the trunk of a taxi near the St. Regis Bali Resort.

Schaefer is still serving out the remainder of his 18-year sentence; Indonesian authorities found him guilty of bludgeoning Mack's mother to death.

Federal prosecutors alleged that Mack and Schaefer beat Sheila von Wiese-Mack to death and that the couple intended to tap into von Wiese-Mack's $1.5 million estate when she was dead. Mack's father, James Mack, was a famous jazz composer who passed away in 2006.

Prosecutors also have alleged that Schaefer "received advice from his cousin, Ryan Bibbs, about how to kill Von Weise," according to the indictment. Bibbs pleaded guilty in December 2016 to one count of conspiracy to commit foreign murder of a US national, according to prosecutors.

The three-count indictment also included an obstruction of justice charge. Prosecutors allege that Mack and Schaefer "destroyed, mutilated and concealed objects" related to the murder, forced "the body of [von Wiese-Mack] into a suitcase after she had been killed," and removed "linens and items of clothing worn during the killing … from the place of the murder."

The Chicago Sun-Times reported that ahead of the killing, prosecutors alleged that Mack and Schaefer had exchanged "giddy" text messages anticipating the murder, calling each other Bonnie and Clyde, and using "saying hi" as code for killing.

Wednesday's unsealed indictment is the latest development in a seven-year legal saga surrounding Mack and Schaefer.

While on trial abroad in 2015, Mack gave birth to the couple's daughter, Stella, who lived with her in the cell until the baby was 2-years old. In 2017, Stella was placed in the custody of an Australian woman who was Mack's interpreter, until Mack's release.

On Tuesday, Mack's attorney Brian Claypool said "it's gonna be a war," if Mack was arrested after her deportation from Indonesia, according to the Sun-Times.

Insider reached out to Claypool for further comment.

If convicted on the charges, Mack and Schaefer could face a maximum sentence of life in prison.