Honolulu police charged a Hawaii State Hospital patient with second-degree escape after he fled from a hospital outing.  Chad Nishihira escaped from a supervised activity in Waikiki Friday evening.

Staff members immediately notified police.

According to Dr. William Sheehan with the Department of Health, "There was an opportunity for that person to leave without permission and not be directly in eyesight of the staff."

Sheehan said the outings help rehabilitate patients.

Nishihira, who was acquitted of manslaughter in 2008, was free for almost 24 hours.

He eventually returned to the Hawaii State Hospital on his own Saturday night.

However, the state hospital failed to notify police Nishihira was back in their custody.  Police did not find out until Wednesday Nishihira had returned.

The Department of Health admitted to KITV4 News, not contacting police was an oversight and they are trying to figure out what went wrong.

"We take our responsibility to the community seriously and when something like this happens, we do internal reviews of protocols and policies and risk management functions and we are in the process of doing that," Sheehan said.