The U.S. FBI is assisting Indonesian police in the case of a Chicago woman whose body was found in a suitcase in Bali. Police has arrested her daughter as one of two suspects. (Reuters)

A Chicago-area teen and her boyfriend could face execution by firing squad if charged and found guilty in Indonesia of the premeditated murder of the girl’s mother.

Sheila von Wiese-Mack was found battered and stuffed, half-naked, into a suitcase at a Bali resort hotel on Tuesday. Von Wiese-Mack’s 19-year-old daughter Heather Lois Mack and the girl’s 21-year-old boyfriend, Tommy Schaefer, have been detained by Indonesian authorities since Wednesday; according to Reuters, they have been “formally designated” in connection to the murder.

In Indonesia, suspects are not charged until the investigation is complete and the trial has begun.

“According to the police, yes they will stand trial for murder but due process must be followed first,” Haposan Sihombing, an Indonesian lawyer assigned to the couple, explained to Reuters.

Authorities haven’t yet pressed charges against Mack or Schaefer but have confirmed that they are investigating whether von Wiese-Mack’s killing was premeditated, a crime that comes with a death penalty sentence.

“Did they prepare the suitcase before the murder? Did they leave the room to prepare weapons? The investigation still has a long way to go,” said police spokesman Hery Wiyanto, according to Reuters.

According to Amnesty International, Indonesian death sentences are carried out by firing squad:

The prisoner has the choice of standing or sitting, and can decide whether to have their eyes covered by a blindfold or hood. Firing squads are made up of 12 people, three of whose rifles are loaded with live ammunition, while the other nine are loaded with blanks.

Von Wiese-Mack’s body was discovered after Mack and Schaefer allegedly brought several pieces of luggage out of the hotel to a waiting taxi. They went back into the hotel and never returned. The taxi driver, who was waiting for the couple, eventually opened the trunk to find a bloody, grey, hard-shelled suitcase in the back.

An Indonesian police officer escorts Tommy Schaefer, left, as he is brought to the police station for questioning in relation to the death of his girlfriend's mother, in Bali, Indonesia, Wednesday, Aug. 13, 2014. The body of a 62-year-old American woman was found stuffed inside a suitcase on the Indonesian resort island of Bali. Police arrested Schaefer and Heather Mack, the victim's daughter in relation to the death. Sheila von Wiese Mack's body was found Tuesday inside the trunk of a taxi parked in front of an upscale hotel in Bali's Nusa Dua area. (AP Photo/Firdia Lisnawati) An Indonesian police officer escorts Tommy Schaefer, left, as he is brought to the police station for questioning in relation to the death of his girlfriend’s mother, in Bali, Indonesia, Wednesday, Aug. 13, 2014. (AP Photo/Firdia Lisnawati)

Police said that Mack and Schaefer were seen leaving the hotel through a beach behind the facility. Police said earlier that morning, surveillance video showed von Wiese-Mack and Schaefer arguing in the hotel’s lobby.

Von Wiese-Mack’s autopsy showed injuries to her face from a blunt object, according to Reuters, and signs of a struggle, the Associated Press reported.

“We found scars on both forearms and the broken left-hand fingernail,” Head of Forensics Ida Bagus Putu Alit said, according to the AP. “That indicated a resistance in a fight.”

At one time, von Wiese-Mack and her daughter lived in an upscale Chicago suburb. But behind closed doors, there was turmoil, according to police reports. Police were called to the house 86 times since 2004, according to the Chicago Tribune.

Von Wiese-Mack is the the widow of well-known Chicago composer and producer James Mack, who died of a pulmonary embolism in 2006 while on a family vacation in Greece.

Neighbors and friends described a volatile mother-daughter relationship.

“Police were here all the time,” one neighbor told the Chicago Tribune. “They would call police on each other. It turned very abusive and volatile.”

The battered body of a 62-year-old American woman was found stuffed into a suitcase in Bali, Indonesia. Police have arrested the woman's daughter and her boyfriend. (Reuters)