The California man accused of killing Australian tourist Matthew Bate in an early morning one punch attack in San Francisco has wept during his first court appearance.
David Murillo, described as a "gentle, hard-working" father of two young daughters from the Californian city of Hesperia, was in San Francisco working on a specialty drape project when he had a 2am confrontation with Mr Bate outside a hotel on Friday.
Mr Bate, 33, from Darwin, was on holiday in the US.
Murillo, 34, allegedly punched Mr Bate, who fell to the ground, struck his head, and died later in a San Francisco hospital.
Murillo entered not guilty pleas on Tuesday to felony counts of involuntary manslaughter, assault and battery during his emotional arraignment in the Superior Court in downtown San Francisco.
Murillo's lawyer, Mark Jacobs, said his client may appear big and strong, but "he's really a gentle guy" who had been weeping.
"He's in shock," Mr Jacobs told reporters.
"He's a gentle, hard-working man with two little girls.
"He has never been in trouble in his life and now he finds himself in a (jail) holding tank."
Murillo was granted $US100,000 ($A133,000) bail.
Police originally booked Murillo into the county jail on a felony count of murder, but prosecutors, after assessing the evidence, charged him with the three lesser counts.
"Given the totality of what happened here the basis of the charge is a single punch and that is why we charged him with felony involuntary manslaughter, battery and assault," District Attorney spokesman Alex Bastian said.
Murillo was ordered to return to court on June 14 for a status update.
Mr Bate, an analytical chemist and keen cricketer, was originally from Ocean Grove in Victoria but had recently been living in Darwin.