Officer Ethan Ferguson, 39, of Hilo has been charged with two counts of second-degree sexual assault and three counts of fourth-degree sexual assault, the Hawaii Police Department said.
"My first thought was somebody really blew it in DLNR," Hawauud state Sen. Will Espero told CNN affiliate KHON.
"Something motivated someone to take the recommendation of a county law enforcement agency on one of its former employees and basically disregard that suggestion."
Ferguson and his attorney couldn't be immediately by CNN for comment this week. Ferguson has been a conservation and resources enforcement officer since June 27, 2013.
Ferguson had earlier worked for the Honolulu Police Department, which recommended against his hiring at the state agency, said Honolulu police spokeswoman Sarah Yoro.
Yoro didn't detail the reasons for the negative recommendation.
"The department also listed 'discharge' as the reason for termination and stated that it would not recommend his hiring," Yoro said. "There is no record of (Hawaii Department of Human Resources Development) contacting the HPD for additional information."
The Department of Land and Natural Resources is now reviewing its recruiting practices, Director Suzanne Case said in a statement.
"State hiring agencies including Dept. of Land and Natural Resources carefully review criminal records and all information provided prior to hiring selected candidates," Case said.
"While we cannot comment on ongoing investigations, we are taking a look at all aspects of our hiring processes, particularly for law enforcement positions, to identify areas where heightened scrutiny can be added to ensure we have the best candidates possible for available positions," she added.
Meanwhile, Ferguson has been served with a letter of removal of police authority and is now on administrative leave with pay, pending the outcome of the court case, the DLNR said.
A female minor alleged that a DLNR officer approached her at a state beach in Hilo on January 1 and then sexually assaulted her, authorities said.
Ferguson was arrested six days later, authorities said. Ferguson was released after posting $13,000 bail, authorities said.
The state police agency is continuing its investigation, and the DLNR Division of Conservation and Resources Enforcement is conducting its own inquiry.
Ferguson and 108 other Hawaii officers like him have powers to enforce laws and rules in state parks, lands, historic sites, forest reserves, aquatic life areas, conservation districts and coastal zones, the DLNR said.