By Shelby Sebens

PORTLAND, Ore. (Reuters) - An Oregon judge has acquitted a 61-year-old man who admitted taking photographs up the skirt of a 13-year-old girl as she shopped at a Target store in suburban Portland, lawyers in the case said Friday.

Washington County Circuit Court Judge Eric Butterfield ruled on Thursday that Patrick Buono did not break the law when he surreptitiously took the pictures of the girl in January 2013, said his defense attorney Mark Lawrence.

"He did not deny it and he feels real bad about it too, by the way," Lawrence said.

The girl did not notice his actions, Lawrence said, but another woman in the store alerted officials and film from surveillance cameras later confirmed Buono's act.

The practice of "upskirting" has caused problems for prosecutors in other court cases where there are no laws on the books preventing people from taking unauthorized pictures up the skirts of clothed women in public places.

Prosecutors accused Buono of attempting to engage in criminal conduct and charged him with invasion of privacy and attempted encouraging child sex abuse.

Washington County Deputy District Attorney Paul Maloney said the girl, now 14 and testified against Buono in court, was shocked by the incident. He said he was disappointed by the judge's decision.

"She's a great kid," Maloney said. "She's got a great family and what she did the other day was really brave and I'm proud of her. I think she's a mature, young girl and she's doing the best she can with this."

Lawrence said he filed for an acquittal in the case because there was no Oregon law that Buono had violated.

Maloney said he thinks lawmakers could provide more clarity, "but it was clear what conduct the defendant engaged in."

(Reporting by Shelby Sebens; Editing by Daniel Wallis and Doina Chiacu)