WARSAW, Mo. -

A state prison inmate was charged this month with murdering a teenager from Greene County 13 months ago.   Anthony Balbirnie also is charged with five other charges related to the death of Khighla Parks, whose body turned up in Truman Lake near Warsaw.

The charges were filed here in Benton County by the Missouri Attorney General's Office, although most of the six crimes happened in Dallas County.  Prosecutors from Polk, Dallas and Benton counties asked the attorney general's office to help them work on the case late this summer.

Khighla Parks, 15, disappeared from an area near her home south of Willard on Sept. 20, 2012.   A boater found her body in Truman Lake on Sept. 30.    Investigators now think she died on Sept. 21 and Balbirnie put her weighted body in the lake that same day.

Balbirnie was charged in October 2012 with abandonment of a corpse.   That charge was dismissed late this summer after the Attorney General's Office entered the case.

A law enforcement officer familiar with the case has long said privately that he thought enough evidence existed to file a murder charge, but detectives were never able to convince Dallas County Prosecuting Attorney Barbara Viets to file that charge.  No information is available in the charging statement that says whether any new information has recently come to light that led to the filing of the murder charge and the other charges.  Viets has never commented about the case.

Investigators say they learned Khighla was alive on Sept. 21, 2012, at a home at 810 Locust Street in Buffalo, a place that the charging statement calls "a public nuisance."  The charges say investigators believe Balbirnie took Khighla there from Greene County to engage in "asphyxiation sex."

The charging statement says investigators believe Khighla died while she and Balbirnie were having sexual relations and, “in the course of such offense, defendant inflicted serious physical injury.”  Khighla died of asphyxiation, the documents say.

After the death, two assistant attorneys general said in the charges, Balbirnie hid bedding, clothes and Khighla's "personal effects" to try to impede the investigation of her death and the prosecution of Balbirnie and a woman named Amy Hartley.   Online court documents in other cases show Hartley lives, or used to live, at 810 Locust in Buffalo.  

The Attorney General's Office hasn't said whether Hartley is charged or might be charged.  It's possible she is, however.  The Benton County Circuit Clerk's Office gives the same noncommittal answer to questions about documents related to Hartley and Balbirnie.

Investigators have long said they believed Khighla left Greene County willingly, which is the reason no charges were filed for her disappearance in Greene County.

Only the charging statement is a public document.   Nanci Gonder, the press secretary for Attorney General Chris Koster, said the charges were filed on Oct. 17 but have been sealed until now.  The charge still doesn't show up on Casenet, the online database of court cases in Missouri, and the probable cause statement is sealed to the public.  Gonder says that's to "protect certain witnesses."

Balbirnie is charged with second-degree murder, statutory rape, child molestation, child endangerment, tampering with physical evidence, and abandonment of a corpse.  The charging statement says the murder, rape, and molestation occurred in Dallas County.  It says the child endangerment occurred in Greene and Dallas counties, the tampering with evidence occurred in Benton County, and abandonment of a corpse happened in Dallas and Benton counties.

The Benton County Circuit Clerk's Office says Balbirnie has not appeared in court on the charges filed on Oct. 17, and no court date is scheduled.

Balbirnie has been in a state prison since the fall of 2012 on unrelated charges.  He’s serving time for violating his parole on past convictions, which include use and distribution of illegal drugs, assault, and driving with a revoked license.  He left prison on parole in August 2012, a month before Khighla disappeared, and then was returned to prison after being charged with abandonment of a corpse.

Greene County prosecutors in Springfield charged Balbirnie last April 11 on additional unrelated charges of resisting arrest, burglary, robbery and armed criminal action.  Those crimes occurred, the charges say, in September and October 2012.  Those cases are pending.