NASHVILLE, Tenn. -- A Metro police officer has quit after 17 years following allegations that he had an inappropriate sexual relationship with a child.

Officer James Stackhouse joined the Metro Police Department in September 1992. He was a field training officer with the Hermitage precinct until last Tuesday, but his career as a police officer began to unravel Sunday night.

"In the early morning of Aug. 3, Officer Stackhouse was called in and was presented with the allegations and was questioned or talked to about the allegations," said Metro police spokesman Don Aaron. "They were very serious, and a situation like this warranted his immediate decommissioning and the admonishment that disciplinary action would begin immediately."

Sources told Channel 4 News the child involved is a 12-year-old girl who lives in Wilson County but that the Clay County Sheriff's Office is handling the investigation since the alleged incident happened on Dale Hollow Lake.

Metro police said they informed Stackhouse of the allegations on Monday morning and that he submitted a one-sentence, handwritten resignation Tuesday.

"He did not work in between the third and the fourth," Aaron said. "He was decommissioned or had no police power from the point that he was informed of the allegations."

Stackhouse's personnel file shows a number of commendations and that he won Officer of the Month in 2006, 2008 and 2009.

He has been disciplined twice, according to the documents, including a three-day suspension in 2006 for contacting a known felon that he met on duty to pursue a personal relationship.

Channel 4 attempted to get a comment Monday from Stackhouse at his Hermitage home, but the person who came to the door would not answer it.

No charges have been filed based on the investigation against Stackhouse.

Sources said the facts of the investigation will likely be sent to the grand jury.