Updated 08/15/14 – 11:54 a.m.

CHICAGO (CBS) — Police in Indonesia have charged a 19-year-old Chicago woman and her 21-year-old boyfriend with killing her mother in Bali.

CBS 2’s Jeremy Ross reports Heather Mack and Tommy Schaefer were arrested Wednesday, a day after a taxi driver found the body of 62-year-old Sheila von Wiese-Mack inside a bloody suitcase the couple allegedly left in his cab.

An autopsy found cuts on von Wiese-Mack’s forearms, and a broken fingernail on her left hand, indicating she fought back against her killers. Police said she was beaten to death, likely with a heavy glass object.

The couple told police von Wiese-Mack was killed by a gang of robbers, but they managed to escape. Police said their claims contradicted witness statements from the taxi driver and hotel workers.

After initial questioning, Mack and Schaefer refused to speak to investigators without an attorney. Published reports have said police conducted psychiatric tests on the couple to try to determine a motive.

Television images showed Mack laughing while in police custody, and telling reporters “you’re crazy.”

Police said the charges are based on witness statements and crime scene evidence.

Sheila von Wiese-Mack (Credit: Caxton Club)

Sheila von Wiese-Mack (Credit: Caxton Club)

The Sydney Morning Herald reported Mack told police she is pregnant, and was taken to a doctor on Friday to verify her claim.

Von Wiese-Mack and her daughter had been staying in Bali for more than a week — first at Simanyak Hotel before moving to St. Regis — before Schaefer showed up on Monday, and checked in to a separate room.

The couple hailed a taxi Tuesday afternoon, loaded the trunk with their suitcases, and then told the driver they were going into the hotel to check out.

After approximately two hours, when they had not returned, hotel security guards noticed blood stains on the suitcase, and told the driver to take his cab to the police station. That’s where police discovered von Wiese-Mack’s body inside the suitcase, wrapped in a white bed sheet stained with blood.

Hotel security video showed the couple had fled the hotel through a back door after leaving the suitcase in the trunk of the taxi. Mack and Schaefer were tracked down the next day and arrested.

Police said hotel security cameras recorded Schaefer arguing with von Wiese-Mack the night before, but the motive for the murder is unclear.

An Australian newspaper reported the young couple demanded hotel staff open her mother’s safe deposit box when they were trying to check out, but von Wiese-Mack left instructions only she could access it.

Mack’s Chicago-based attorney, Michael Elkin, has said she denies any involvement in the murder. He said Mack called him before her arrest, because she was thinking of going to the authorities for help.

Elkin said he is working to secure her legal representation in Indonesia.

Alberto Arias, a dance instructor who taught Mack for two years, said her mother was “a very supportive person, and really pushed her along in her dance career.”

“The interesting thing is they were amazing together,” he said. “The mother was very soft-spoken, very sweet, and you would never think that there was anything wrong or going on.”

However, police were often called to their former home in Oak Park for domestic incidents – in all, officers visited their Oak Park home 86 times from January 2004 to June 2013, mostly for domestic disputes. Some calls also included missing person reports and theft allegations.

Chicago police also visited their Gold Coast apartment several times for domestic disputes while they were living in the city the past year.

According to published reports, von Wiese-Mack had called police after she discovered the couple had been using her credit card without permission to party at the Conrad Hotel. Schaefer was arrested and Mack was detained last month at the Conrad Hotel on Rush Street hotel, after an employee called police about a disturbance. Chicago police confirmed Schaefer was charged with misdemeanor disorderly conduct and breach of peace. Mack was released without charges.

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