The 13-year-old managed to escape her attacker, running to her mum and telling her what happened.
Whilst being interviewed by police, Roche told officers "my hands have slid up her body, as she slid to the ground".
In court, Roche tried to persuade the judge that chasing the girl into the lift and touching her was just a game.
"My mind has gone off on a tangent like, this is a challenge, to me, I can get her and give her a kiss on the cheek like her two sisters and mum," Roche said in the police interview.
However, the 13-year-old told the court his actions were more than an unwanted kiss and she was scared of her attacker.
She explained that as she cowered under him that he squeezed her breast twice.
In an interview with police, Roche said "my hand slid across there" but claimed there was no sexual intent.
"So there would have been some sort of contact without doubt.
"Certainly no sexual gratification on my behalf.
"She contributed to that occurring by releasing her body weight and sliding through my hands."
The judge found Roche guilty of indecent assault.
The court heard the young girl still has nightmares and lives in fear it will happen again.
Roche, who doesn't believe he did anything wrong, has been suspended from his role with the police force.
SEXUAL HARM - DO YOU NEED HELP?
If it's an emergency and you feel that you or someone else is at risk, call 111.
If you've ever experienced sexual assault or abuse and need to talk to someone contact the Safe to Talk confidential crisis helpline on:
• Text 4334 and they will respond
• Email support@safetotalk.nz
• Visit https://safetotalk.nz/contact-us for an online chat
Alternatively contact your local police station - click here for a list.
If you have been abused, remember it's not your fault.
