Final answer:
The repairman should be arrested for theft or burglary as he had lawful access for repairs but committed a crime by stealing a diamond ring.
Step-by-step explanation:
The repairman who entered the kitchen to replace a leaky faucet and instead stole a diamond ring from the bedroom should be arrested for theft or burglary. Since he had lawful access to the premises for a specific, necessary task, but then exploited this access to commit a crime in a different part of the house, his actions constitute a clear violation of the owner's property rights. The fact that the owner had momentarily stepped outside when the theft occurred does not absolve the repairman of wrongdoing.