Police intercepted phone calls between a toddler's mother and Joel Loffley, the man accused of the murdering the child.
The High Court at Auckland today heard recordings of a series of phone calls between the pair, secretly recorded by police in the days following JJ's death.
Two-year-old JJ, whose full name is James Joseph Ruhe Lawrence, died last November at an Orakei house in Auckland where he lived with his mother Josephine and Loffley.
Loffley has denied murdering the child.
The couple talked about moving north after the case was over, and even mentioned the Kahui twins.
JJ's mother asked Loffley if he knew about the Kahui case.
Loffley responded: "They haven't made any arrests in that yet."
Ms Lawrence replied "That's exactly what we will go through".
In another conversation Loffley told Ms Lawrence that he had something "buzzy" to tell her, but he couldn't say it over the phone.
"I'm scared I'm going to go down for something that I haven't even done."
He also repeatedly asked Ms Lawrence if she blamed him, but stuck to his version of events that JJ fell off the bed while he was "fluffing" the blankets and later died on his sleep.
"This is just too stressful. I'm just kicking myself because I don't know CPR."
The phone conversations between the couple were recorded while they were still in a relationship but living apart.
The court heard last week from Ms Lawrence, who gave details about JJ's short life.
She said JJ had grown up around cannabis. The boy's father - who was in prison when he was born - smoked the class C drug around the home, and so had Loffley.
"Joel used to give him spots ... I probably would have blown smoke in his face but that's about it."
She confirmed she had smoked methamphetamine and used ecstasy but said the drugs came from Loffley who she said sold cannabis.
Ms Lawrence said Loffley was a jealous and violent man who beat her and once throttled her in their kitchen until she stopped breathing.
"He nearly killed me."
Asked by Loffley's lawyer Roger Chambers why she did not leave or phone for help, Ms Lawrence said she came close to leaving him but found out she was pregnant and wanted to stay for the child that was on the way.
" ... I loved him at the time and love makes you do stupid things."
The court has heard that Loffley told police JJ had been bouncing on the bed when he fell off and landed on his chest.
Mr Chambers asked Ms Lawrence if she had "lost it" and been violent with her son.
Ms Lawrence denied ever hurting him.
Mr Chambers also asked questions about JJ's funeral, and whether she had told Loffley "I did it".
Ms Lawrence replied: "I didn't say that. If he says that, he's wrong and he's a liar."
She said the night of the funeral, she and Loffley were in bed.
"He asked me: 'Do you think I did it?' and I said: 'Yes'."
Ms Lawrence confirmed she had said to her cousin she might get between five and six years in prison because JJ's death had been an accident.
"I said that because I felt I was to blame, even though I didn't do anything. I felt like I was to blame because I am the mother."