A crime scene investigation is ongoing at Cuyahoga Valley National Park in Ohio, where hikers stumbled across parts of a human skull and jawbone.

At this point there are more questions than answers to the mystery, which arose Monday when the bones were discovered along a trail in the Valley Picnic Area of the park. Investigators haven't indicated how long the bones might have been there, or whether a murder was commited in the park or a body dumped there after the fact.

The National Park Service is the lead agency on an investigation with support from the FBI Evidence Response Team and the Summit County (Ohio) Medical Examiner’s Office.

Two hikers reported finding a possible human jawbone near the Valley Picnic Area about 5 p.m. Monday. The Park Service subsequently confirmed that the remains were human and initiated an investigation. On Tuesday, the FBI Evidence Response Team began a search of the area and found additional human remains and clothing, a park release said.

The identity of the victim and cause of death are not known at this time. However, the case is being treated as a homicide until proven otherwise.

The Valley Picnic Area is located on Riverview Road in Boston Township. The Valley Picnic Area and Oak Hill Trail System are closed until further notice.

Cuyahoga Valley National Park encompasses 33,000 acres along the Cuyahoga River between Cleveland and Akron, Ohio. Managed by the National Park Service, CVNP combines cultural, historical, recreational, and natural activities in one setting.