An Australian who allegedly killed a grandfather after throwing a $40 wine bottle off a 35-storey Singapore high-rise balcony fears reprisal attacks if he is released from jail.

Andrew Gosling, 47, is undergoing psychiatric assessment and is in a fragile emotional state since he was charged with killing 73-year-old Muslim Nasiari Sunee, according to his lawyer.

Speaking with nine.com.au , Singaporean lawyer Gloria James said many Singapore locals were angry at Mr Gosling, who remains detained in Central Police Division.

Andrew Gosling, 47, has been charged over the death of a grandfather in Singapore. (9News)

The psychiatric report will establish if Mr Gosling, who faces five years in prison, is fit to enter a plea.

A court hearing in two weeks could decide if Mr Gosling wins bail - however he may choose to remain locked up. Nine.com.au understands Mr Gosling is incarcerated in a cell with three fellow inmates.

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"There's a possibility Andrew might not wish to be bailed out," Ms James said.

"He fears for his safety."

Ms James said she met Mr Gosling in her law firm's offices twice before the Australian IT specialist handed himself in to police.

"He was clearly distraught and was suffering. He trembled and shook as he spoke. He was also in tears as he did not expect his act to cause the death of someone."

Singapore Police allege Australian Andrew Gosling threw a wine bottle 15 metres from a 7th floor balcony, which then hit and killed Nasiari Sunee, aged 73. (9News)

Nasiari Sunee, pictured with members of his family, died after he was struck on the head with a wine bottle just before eating dinner with family and friends. (9News)

How was Singaporean grandfather Nasiari Sunee killed?

Mr Gosling allegedly lobbed a Polissena Il Boro 2016 wine bottle from his seventh-storey balcony towards a fifth-floor public barbecue area of the Spottiswoode 18 condominium, according to court documents.

The flying bottle struck Mr Nasiari on the head as he was about to eat dinner with his family. After suffering multiple heart failures, he died in hospital the next morning, on August 19.

When asked why Mr Gosling had allegedly thrown the bottle, Ms James called it an "act of mischief".

She said Mr Gosling intended to plead guilty.

Ms James is working with prosecutors in an attempt to reduce Mr Gosling's charges to causing death by negligent act.

She is also hopeful, pending bail, Mr Gosling could be allowed to return to Australia while awaiting trial. The judge would need to be convinced the Australian, who relocated to Singapore only two months ago, was not a flight risk.

Mr Gosling had waited 10 days before he surrendered to police, on August 28.

He handed himself in after Singapore police had swept the 35-storey high-rise, questioning residents and requesting they give fingerprints.

Ms James said she did not know why Mr Gosling had not contacted police immediately.

"I believe he did not realise the severity [of what happened], perhaps he was not aware until fingerprints were being taken from residents. Perhaps he was just fearful and had no one to turn to as he was alone in Singapore."

Mr Gosling faces five years in a Singapore prison if found guilty of causing death by rash act.

A Department of Foreign Affairs and Trade spokesperson told nine.com.au they were providing consular assistance to an Australian man detained in Singapore.

The 35-storey Spottiswoode 18 condominium; Nasiari Sunee, pictured with his wife, died after being hit in the head with a wine bottle allegedly thrown from the high-rise's 7th floor. (Ronny Chin & Associates / Supplied)

An example of the $40 Italian wine bottle Singapore Police found intact next to Nasiari Sunee's body on the night he was fatally wounded at a Singapore high-rise building. (9News)