The state confirmed it is conducting a criminal investigation of Dr. Lilly Geyer, the Kailua dentist whose 3-year-old patient died after a dental procedure in December.

Toni Schwartz, Department of Public Safety spokeswoman, said Tuesday that Public Safety’s Narcotics Enforcement Division is investigating Geyer, but could not release further details because the case is ongoing.

Finley Boyle was at Geyer’s practice, Island Dentistry for Children, for treatment of cavities and baby root canals on Dec. 3, 2013, when she stopped breathing in the dentist’s chair and suffered severe and permanent brain damage. Boyle never regained full consciousness and died Jan. 3.

The drugs given to sedate Boyle likely caused her death, an autopsy determined.

Boyle’s parents sued Geyer, alleging negligent and dangerous conduct in sedating their daughter, and failing to prepare for or respond appropriately to the medical emergency.

No criminal charges have been filed against Geyer.

Geyer is also the subject of an administrative investigation by the state’s Regulated Industries Complaints Office, which filed a motion on July 24 to order Geyer and her attorney to make employees available for testimony about the case. Documents in that motion disclosed the criminal investigation.

State law authorizes the Regulated Industries Complaints Office to investigate any person who furnishes services for which a license is required.

Daria Loy-Goto, the state complaints and enforcement officer, said her office conducts administrative investigations that are brought before the licensing boards, which can dole out punishments ranging from fines to the revocation of a license.

Fines for a dentist can run up to $5,000, she said, adding that a professional whose license is revoked cannot reapply for a license for five years.

According to court documents, a state field investigator with the complaints office twice requested to interview four current or former employees. Geyer’s attorney, John Nishimoto, responded in March, saying Geyer and her employees could not be interviewed because of a criminal investigation and civil lawsuit.

On April 10, the field investigator served two subpoenas on Geyer’s attorney for two witnesses to appear and testify at an April 11 hearing.

The same day the subpoenas were served, Nishimoto responded in a letter that the state’s Narcotics Enforcement Division is conducting a criminal investigation into Geyer "as a result of the care and treatment provided to patient Finley Boyle."

Nishimoto acknowledged that it is not in his client’s best interest to delay the complaints office’s investigation and he would let the investigator know when the employees can be interviewed.

Nishimoto also said that Geyer is not using her dental license and asked why the state would continue an administrative investigation if Geyer surrendered her license as the state suggested.

Nishimoto did not immediately respond to an email request for comment.

Loy-Goto said the state will continue pursuing a case even if a license is relinquished, to determine whether malpractice was involved in case the professional seeks another license.

Geyer’s dental clinic closed in January.

A hearing on the motion to compel Geyer’s employees to testify has been set for Aug. 29 before Circuit Judge Rhonda Nishimura.