Body in suitcase: Boyfriend Tommy Schaefer confesses to murder of Sheila Mack

POLICE have revealed the motive for a pregnant teenage girl"s alleged murder of her mum in Bali, whose body was stuffed into a suitcase.

Denpasar police chief Djoko Hari Utomo said that the motive for the murder appeared to be that Heather Mack"s boyfriend, Tommy Schaefer, was "offended” by the victim, Sheila Mack.

But Utomo would not elaborate in what way or how Schaefer felt offended by Sheila Mack, who was then murdered.

He also revealed that Heather Mack, who has been accused of murdering her mother, had so far confessed to witnessing the murder. AP reports police chief Col. Utomo as saying that Schaefer had also confessed during an interrogation on Monday.

Col. Utomo said police were still investigating the case but so far intend to charge the pair with premeditated murder, which carries the maximum death penalty, and with murder, which carries a 20-year maximum.

Heather Mack has seen the ultrasound image of her unbo baby and has told of her fears for the infant"s future if she is jailed. Mack, 19, is now 12 weeks pregnant and this week was taken to a Bali police hospital for an ultrasound.

One of her local lawyers, Lily Lubis, was with her at the examination along with an American lawyer who has flown to Bali to represent Mack and the rights of her unbo child as she fights allegations that she and her boyfriend brutally murdered her wealthy mother, Sheila von Weise Mack, in a five-star resort while on holiday.

Details of her pregnancy were revealed to News Corporation after her arrest.

Ms Lubis, who also represented Schapelle Corby, was with Mack at the hospital.

"The baby has been formed. We can see the feet and hands,” Ms Lubis said.

She described Mack"s reaction to the image on the screen as "happy and surprised”. Mack said excitedly said "my baby” when it appeared on the monitor.

Ms Lubis said Mack talked repeatedly of her conces for the baby"s future.

"She said that she feels worried. She has always said that she fears if she must treat her child in jail. I think it is normal for a pregnant woman facing a case like this, to feel like that. She really wants to be a good mother for her child,” Ms Lubis said, adding that Mack was still in shock.

Mack has had cravings for ice cream since being jailed as well as chocolate and is now receiving milk and prenatal vitamins, provided by her legal team.

Police escort ... Mack was taken for psychiatric evaluation after charges were laid. Source: Supplied

The teenager was this week interrogated by police over the murder of her mother, whose body was found stuffed into a suitcase which had been dumped into a taxi on August 12.

Mack and her mother, Sheila von Wiese Mack, 62, a wealthy Chicago socialite and widower, were on holiday at the St Regis Resort in Nusa Dua last month when the murder occurred. Police allege that Mack and her boyfriend, Tommy Schaefer, lugged a silver suitcase through the hotel"s lobby and placed it into the boot of a waiting taxi before disappearing.

The taxi driver waited for several hours and then went to police after blood began seeping out. Mrs Mack"s body was found stuffed inside. An autopsy found she had suffered broken bones and blunt force trauma from objects, believed to be a glass ashtray and fruit bowl in the hotel room. Authorities said she had defensive wounds, indicating she had fought hard for her life.

Mack and Schaefer were arrested at a Kuta hotel where they had checked in allegedly using Mrs von Weise Mack"s credit card.

Mack and Schaefer initially told police that masked Indonesian intruders were responsible for the killing.

Slain ... Sheila von Weise Mack"s body was found bludgeoned in a suitcase. Source: Supplied

Mack was questioned by police all day on Wednesday and again yesterday as they further the investigation.

Police intend processing the case and pursuing murder charges against the pair.

The Indonesian lawyer representing Schaefer resigned yesterday, indicating conflict and saying he could not handle the case independently.

Mack has two American lawyers representing her along with Ms Lubis and another Bali lawyer but they are not representing Schaefer.

The pair have yet to be officially charged. Their initial detention period of 20 days has been extended for another 40 days and they will not be officially charged until they appear in court.