Federal investigators called in as Colorado firefighters make progress

COLORADO SPRINGS, Colorado (CNN) -- As hundreds of firefighters began to get the upper hand on a huge blaze near Colorado Springs, investigators stepped up their probe into the cause of the most destructive wildfire in the state's history.

Investigators are treating the 16,000-acre Black Forest Fire, which was 75% contained Monday, as a crime scene, though they don't yet know whether a crime was committed, El Paso County Sheriff Terry Maketa said.

Authorities are allowing more people to visit their homes by the day -- the mandatory evacuation area covered the homes of 4,100 people Monday, down from tens of thousands last week. But Maketa asked for patience from those still being kept out, citing not only the remaining hot spots, but also the need to preserve evidence.

"When you're talking about a potential for prosecution -- we don't know yet whether it's a crime or not -- we're going to treat it as (if) it is, and preserve every element of that scene as we can," Maketa told reporters Monday. "To allow people go in and trample through ... compromises our scene."

Courtesy CNN

The Bureau of Alcohol, Tobacco, Firearms and Explosives has been called in, along with state authorities.

"We are zeroing in on the point of origin, and it's a very slow, methodical process," Maketa said. "We brought in additional experts to make sure we're not missing anything ... but I'm pleased with the process they are making."

Maketa's comments came after fire teams made significant progress against the flames northeast of Colorado Springs over the weekend, with containment growing from 5% to 75% in just a few days' time.

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