Friends and police records have revealed disturbing portraits of two US citizens arrested in Bali last week for the alleged murder of a woman whose body was stuffed in a suitcase.

Tommy Schaefer, 21, and Heather Mack, 19, were arrested for the murder of Ms Mack's mother Sheila von Wiese-Mack whose remains were found in a bloody suitcase in the back of a taxi.

The 62 year old's body was discovered last Tuesday outside the upmarket St Regis Hotel in the Nusa Dua tourist area.

The couple were arrested the following day as they tried to leave the hotel. But the relationship between the mother and daughter was a troubled and often violent affair, which included broken bones and constant threats from the daughter, the Chicago Sun-Times reports.

Police documents reveal Ms Mack repeatedly bit her mother, imprisoned her in her room and on one occasion broke her arm by pushing her to the ground.

Ms Mack told her widowed mother at one point she would start hitting her in the head in order to "stop leaving bruises", one police report states.

Police were called to their residence 86 times over a 10-year period, but the mother insisted she did not want her daughter to go to jail because she believed it would not help her.

Friends of Mr Schaefer also described a troubled man who lied and manipulated friends and their parents, OakPark.com reports.

"He was always into the drama," the mother of one friend told the website, describing him as a bad influence.

"I caught him lying to my face a number of times."

Friends did not give their names to the website, but they described a teenager often on the periphery of social circles who stretched truths to win people over — especially girls.

The mother of one of Mr Schaefer's ex-girlfriends said at one point he spun a story about a potentially-fatal heart condition.

"He could definitely be emotionally manipulative," she said.

Another ex-girlfriend spoke of how Mr Schaefer, an aspiring rapper who goes by the name Tommy Exx , wrote a song for another ex-girlfriend who died in a car crash in South Africa.

Body of American tourist found in Bali (Getty)

"He told me part of his heart had died…It was hard for me to see him like that," she said.

He sold the song on iTunes and was giving the money to charity, the ex-girlfriend told the website.

The suspected killers are facing a maximum penalty of death, but a lawyer for Ms Mack — who it was revealed is two months pregnant — said the allegations against his client were false.

"Said allegations and reports are not true and will be disproven as the investigation continues or at the conclusion of trial, if formal charges are indeed filed," the lawyer said in a statement.

On Saturday an FBI agent was dispatched to Bali to assist with the investigation.