GLENWOOD | The Cook County Sheriff's Department is investigating a Glenwood cemetery after a delivery worker discovered a human bone near the cemetery's vaults, sheriff's officials said Saturday.

The worker was dropping off vaults Friday morning at Mount Glenwood Memory Gardens South, 18301 E. Glenwood-Thornton Road, when he noticed a bone about 10 inches long lying on the ground nearby.

The worker contacted sheriff's police, who took the bone to the Cook County medical examiner's office, which determined it was of human origin Saturday. The bone was found among old headstones in an area that cemetery visitors typically do not walk through, officials said.

The investigation into Mount Glenwood comes five days after a South Side family filed a civil suit against the cemetery. Chiquita Ratcliffe, Phyllis Pearson and Zechariah Thomas III allege the cemetery dug up and relocated the remains of two of their relatives. The family discovered a missing headstone while visiting the grave in late June.

Mount Glenwood management said the family's headstone merely had sunk and called the lawsuit frivolous. However, another cemetery visitor, whose relative is buried near the family's plot, said cemetery officials told her the grave in question was empty, according to the lawsuit.

The family filed suit to exhume the bodies to determine if the relatives still are buried at the cemetery, according to Bardia Fard, the family's attorney.

Steve Patterson, spokesman for Cook County Sheriff Tom Dart, said officials do not know whether there is a correlation between the civil suit and the human bone found Friday.

"The sheriff's department will now start an investigation, which will include interviewing those working at the cemetery, among others," he said in an e-mail Saturday night.

The sheriff's department does not have reason to close the cemetery at this time, Patterson said, and does not know how long the investigation will take.

"I don't know whether this is a sign of a greater problem or if there is a valid reason why this bone was found where it was," Patterson said.

The investigation into Burr Oak Cemetery in Alsip lasted six weeks before charges were filed and the cemetery closed, he said. Four employees of the historical black cemetery since havebeen arrested and charged with digging up graves and reselling plots.