FAIRFAX COUNTY, Va. (WJLA) - For the past four days, police cruisers have been hard to miss in an area of Fairfax County near Annandale.
They've been traveling in and out of Holmes Run Spring Park off of Columbia Pike since Saturday, connected to an investigation that has many asking questions, but remains a mystery.
About a half-mile inside the park, past the stream and beyond the construction site, evidence response teams from the FBI have been collecting evidence since Saturday - but the Bureau will not say what investigators are looking for, or what they've found so far.
They will only say that it's part of a long-term, ongoing investigation.
A spokesperson with Fairfax County Police says the department is only on scene to assist the FBI.
Nearby resident Ron Graves says police aren't usually in the area.
"They don't do a lot of patrolling in this park," he told ABC7.
When asked he he thinks that is, Graves replied, "Because we don't have anything noticeably bad happening. It's kind of unusual.
Like so many others around here, Demi Pulas is curious about what's going on - but he's patient, not panicked.
"I suspect we'll find out sooner or later, when they're ready to tell us."