John Chardon shot his wife in the back of the head and weighted her dead body so he could dump it in the Southport Seaway, convicted conman Peter Foster claims.
Foster appeared in Brisbane Magistrates Court on Thursday and gave a second day of explosive evidence in the Gold Coast businessman's committal hearing.
His police statement, obtained by AAP, also revealed Foster claimed Chardon confessed he took Novy Chardon's body to the seaway when the tide was going out at night after he killed her in February 2013.
Foster said he asked Chardon how he could be sure her body wouldn't be seen by fishing boats or in the moonlight.
"I weighted her with moderate weights so she would go under," he alleged the Gold Coast businessman said.
"I punctured her stomach so gases wouldn't fill up and make her float."
Foster told police Chardon said because Novy was so small, she would have "shot out of the seaway like a submarine torpedo".
While giving evidence, he alleged Chardon had a breakdown on the night of March 31, 2015, while the pair were sharing a jail cell.
Chardon had not been charged with his wife's murder at that point and was incarcerated on other offences.
Foster, who became an informant to get information on the businessman, claimed Chardon confessed to fatally shooting Novy in the back of the head with a handgun for the first time.
"He said: 'A 38 would have blood splatter everywhere ... whereas a 22 may not exit the head. It would roll around like jelly'," he told the court.
Foster alleged Chardon dismissed reports from neighbours they heard two bangs on the night Novy died because he had made a "crude plastic" silencer out of a soft drink bottle that turned "a bang into a pop".
The court heard claims Chardon told Foster he hadn't left a trace of evidence, saying "ammonia and water washes away DNA and forensics".
The sensational allegations followed Foster's evidence on Wednesday that Chardon told him he killed Novy because he didn't want her getting half of his business.
He alleged on Thursday the businessman's motive stemmed from a letter he received from Novy's lawyers that told him to 'get out of the house'.
"He had a planned business trip and he was worried they were going to change the locks. I think he just felt that was the straw that broke the camel's back," he said.
Defence barrister Tony Kimmins repeatedly questioned Foster about his statement and how it didn't appear to match up with the notes he took in jail.
Mr Kimmins asked Foster if he was aware there was just one recording of the pair's conversations during a six-week period.
"Well that is shocking," he replied.
The court heard there were no details about Chardon's alleged confession on the recording, even though Foster claimed it took place one night earlier.
Mr Kimmins put to Foster he had on several occasions drawn his own conclusions from what Chardon had said.
The hearing is set to continue on Friday.
Australian Associated Press