IT WAS the case of a frightened former heroin addict, a stolen prize winning chihuahua called Harry and his frantic dog breeder owner.

Only Harry knows who stole him at the Royal Adelaide Show.

But chihuahua fancier Khuong Dinh Tran has copped a $400 fine and an 18-month good behaviour bond after police found Harry in his cupboard.

Tran, 33, pleaded guilty in the Adelaide Magistrates Court today to unlawfully possessing Harry, who was stolen from owner Kylie Sunman in September last year.

Magistrate Kym Boxall said Harry was extremely valuable to his owner, who offered a $5000 reward, and his theft at the show caused her immediate and subsequent distress.

"(However) this court is not sentencing Mr Tran for the theft of the dog and the prosecution has made it clear it is not proferring any proof the defendant stole the dog," he said.

The question remains, who stole Harry?

Prosecutor Fred Wojtasik said police could verify only that an "Asian" person was seen leaving with the dog.

The magistrate accepted Tran, who was known to keep the breed, bought the dog from an "Asian" person for $150.

"The payment made for the dog was not unusual, it was within market parameters," the magistrate said.

Tran later panicked at publicity of the stolen pooch and sought advice from an acquaintance, who dobbed Tran in and claimed the reward.

Tran was reluctant to go to police because of previous dishonesty offences relating to a former heroin addiction.

The magistrate said Tran's reluctance prolonged the period of time the dog was missing for his owner.

However he was satisfied Tran was rehabilitated and the dog napping had ended well.

"(It was a) cruel and disgraceful act to remove a show dog from the show."

"The defendant . . . did care for the dog, the dog was safely returned to the owner," he said.

"There was a good final outcome to this theft."

Tran was also ordered to pay prosecution costs and the phone bill of Harry's frantic owner.