As he walked down Hamilton's Victoria St he became aggressive to other members of the public.
The court heard he'd spotted Mr Donker, a 76-year-old man weighing just 46kg, in his Subaru and told an associate he was going to kill him and take off with his car keys.
He asked Mr Donker for food and money, but he replied that he didn't have any and went to the toilet.
Kingi yelled and kicked at the toilet door and when it opened, he punched Donker in the face and hit him on the head with a full bottle of Jim Beam - which weighs about 1.4kg.
He stole his car keys out of his hand as he lay unresponsive on the toilet floor.
Kingi drove off towards Auckland and was spotted by the police on State Highway 1 at Taupiri.
Road spikes were laid near the Meremere dragway and he came to a stop about five minutes later near the foot of the Bombay Hills.
When questioned by police, Kingi told police he'd asked Mr Donker for food and money and wanted to sell his stolen car for $10,000.
A post mortem revealed Mr Donker died of blunt force trauma to the head.
Kingi's other charges of failing to stop and theft of a motor vehicle were withdrawn by police.
Justice Timothy Brewer issued Kingi - who showed no emotion during his appearance - his second strike warning and remanded him in custody to be sentenced on November 23.
Mr Donker's cousin, Harry Donker, earlier told the Herald that Jacques Donker had already endured a tough life and was operating on one lung after winning his recent battle with lung cancer.
Jacques Donker was one of five siblings most of whom still live in and around Hamilton.
"He was a very peaceful guy. A couple of years ago he had lung cancer and they had taken one of his lungs out and it would have been much nicer if he passed away then, rather than what's happened to him now. It's terrible."
When contacted this morning, his sister Sara Donker was unaware that Kingi had pleaded guilty, however she declined to comment on the plea or her brother's death.
Murdered man a convicted paedophile
A Hamilton man murdered in a city toilet was a convicted paedophile.
The Sensible Sentencing Trust confirmed to the Herald that Jacques Donker, also known as Jack, had been on its offender database for many years.
Donker died after Kingi smashed a bottle of Jim Beam over his head after using the London St toilets on August 11.
Trust spokesman Ross Crosby said Donker's death brought to light his horrific offending which spanned 13 years, according to court reports.
In 2004 Donker, also known as Jack Donker, was jailed for four and a half years on two charges of indecent assault and a charge of sexual violation by unlawful sexual connection on a teenage boy.
Donker abused the boy, who had a mental age of 9, over a six-month period.
Donker's history also includes two convictions in Auckland in 1991 for doing an indecent act on a boy and a charge of indecent assault and in 2003 was convicted for lurking and loitering in Te Awamutu.
"Donker's cousin, Harry Donker said the family were aware of Jacques' previous offending, but said he had turned over a new leaf after his conviction in 2004.
"We can confirm Donker was an offender listed on the SST offender database and has been listed on there for some years now. Donker's full sentence will have ended around September 2008 but became eligible for parole at two-thirds of the term but we don't know the actual date of release."
- Additional reporting: Newstalk ZB
