Police this morning withdrew a raft of charges and Kearns pleaded guilty to a representative charge of selling the class A drug cannabis, possession of cannabis, and unlawful possession of a firearm.
The police summary of facts said Kearns was at his Southshore home with two friends on November 21 last year when they caught him selling drugs.
At about 1.20pm, Kearns sold some marijuana to an associate who was stopped by police soon after leaving the address.
Officers found him in possession of 11 large snaplock sandwich bags amounting to approximately 300 grams of dried cannabis.
Ten minutes later, a female associate walked out of Kearns' house and was found with 96 grams of cannabis leaf that she admitted buying from him for $1400.
At about 1.50pm, another man was caught buying a $20 "tinnie''.
Kearns left the house with two females 10 minutes later and was swooped on by police.
A warrantless search of his house was conducted by police under the Search and Surveillance Act 2012.
A cut down single barrelled sawn-off shotgun was found in a black backpack inside his wardrobe. Kearns is not the holder of a firearms licence.
Also in the wardrobe, was a 20 litre plastic bucket containing nine snaplock bags of "good quality dried cannabis head" weighing approximately 249 grams.
A large supermarket bag was also in the bucket with a further 174 grams of similar quality cannabis, which had not been packaged for sale.
In explanation, Kearns admitted joint custody of the firearm, stating he had it for his own safety. He owned up to selling the cannabis, the summary says.
Police are seeking forfeiture of $5490 in cash found in Kearns' possession after his arrest.
Judge Jane Farish remanded him on continued bail for sentence on April 17.
She called for reports to consider an electronically-monitored sentence but warned that was no guarantee he would not receive a jail term.
In November, Kearns - who testified against his mother in her murder trial last year - won $55,000 from Milner after she framed him and put him behind bars.
Milner admitted perverting the course of justice and was jailed for two years and eight months when she sent herself death threats and claimed they were from her son.
Kearns was arrested and spent 18 days in custody - including his 19th birthday - while it is alleged that police took 13 days to carry out a search warrant which would eventually clear his name.
He has also launched legal action against police for allegedly failing to properly investigate his case.
Milner is currently serving a life term with a minimum non-parole period of 17 years for the murder of Mr Nisbet in 2009.
She has lodged an appeal against her conviction at the Supreme Court.
