Auckland man John Skinner - the man who pulled the air rifle's trigger - was yesterday found guilty of his murder. Co-accused Iain Clegg was found guilty of his manslaughter.
Ms Lawrie told TVNZ's Close Up programme yesterday she believed justice had prevailed over a pair who showed no remorse.
"I'm absolutely stoked; we all are," she said as she left the court.
"I think we will smile for the rest of the day."
She remembered a son who spent years working as a radio technician at New Zealand diplomatic posts and for the United Nations in Bosnia and Somalia.
She was terrified for him while he was away, but pleased when he returned to what she thought would be a quiet job with the police. In New Zealand, "nothing bad happens".
She remembered their last conversation. They spoke the night before he was shot, after he tried to attach a tracking device to a car in South Auckland.
"He said 'I can't talk long, Ma. I've got to get ready to go into town. I've got a job tonight.'
"I said 'Have fun'."
The next morning, she heard a radio report that an undercover policeman had been shot during an operation in Mangere.
She said she knew it was her Donny.
"I couldn't believe it. He had been overseas for so long in dangerous places doing dangerous jobs ... and to come here and be killed in a quiet street in South Auckland."
Before the verdict yesterday, she paid tribute to the undercover people policing "these bad, bad men".
"If we didn't have these men and women out there working in the jobs they are doing, this country would be finished."
She said she was "a vengeful woman ... but I am going to let justice do the vengeance for me".
