PORTLAND, Ore. -- Some real estate agents are concerned that prospective homebuyers could be at a house that's up for sale, and could get in to see it without a licensed real estate agent actually being there.

Robert Brading's condo has been on the market for about a week. It’s set to close next Friday.

He, like many sellers, had prospective buyers in and out of his home. Some properties up for sale have lockboxes protecting the keys to the home. Real estate agents, like Val Thorpe, can open a lock box either with a key card or an app on their phone.

“This is what's getting misused,” said Thorpe as she opened the app. Thorpe is a principal broker with the Hasson Company.

“I could be at my office and my buyer could be standing here at the lockbox and I could generate a code to show this property as if I was standing at the lockbox, give that code to my buyer. My buyer could open the lockbox,” said Thorpe.

“I would hope that agents wouldn't do that,” said Brading.

Thorpe said agents are supposed to be present accompanying possible buyers. Otherwise, Thorpe said the agent needs to get written permission from the seller for anyone other than a licensed realtor to enter the home.

“It's definitely been an issue here.” said Thorpe. “The phone needs to be in proximity to the lockbox."

“You'd hope that agents would police themselves, that they would set standards,” said Brading. “It's always a concern when you have folks wandering through your house who you don't know and you don't know what they might do."

Thorpe said while the majority of agents aren't misusing the lockboxes, the ones who are caught are getting fined for it.

She said over the last year, between five to seven real estate agents have been fined up to $2500.

A spokesperson with SentriLock, the manufacturer of the lockbox, said it is secure and they constantly make improvements to enhance security.