Experts are starting to put together a three-dimensional view of the oil spill -- and what they're finding is more bad news.

Scientists have confirmed the spread of oil from the massive Gulf of Mexico spill more than 40 nautical miles from the disaster site and at a depth of 3,300 feet, a top official said Tuesday.

Experts have completed a scientific analysis of the oil, the head of the National Oceanic and Atmospheric Administration, Jane Lubchenco, told a press conference.

"NOAA is confirming the presence of very low concentrations of subsurface oil at sampling depths ranging from the surface to 3,300 feet at locations 40 to 42 nautical miles northeast of the well site," she said.

Lubchenco added officials have completed a process of "fingerprinting" the oil to confirm that it did in fact, come from the BP spill.

"The test results confirm that there is oil subsurface. We've always suspected that, but it's good to have confirmation," the NOAA chief said.

She said scientists working with NOAA are trying to assemble "a three-dimensional puzzle, so that we can have a better sense of what's where, in what amounts, and what impact it's having," Lubchenco said.

The analysis, which she said is being carried out by NOAA in concert with experts at the University of South Florida, rules out that the oil could have come from any source other than the BP spill.

"We've been tracking where the oil is going at the surface and where it is going below the surface," Lubchenco said, calling the BP oil spill is "a human tragedy and an environmental disaster."

She added however that some oil found 142 miles southeast of the well site had been found in tests to be "not consistent" with the BP oil, explaining some oil was naturally occurring in the Gulf.

Lubchenco said the work to determine just how far the BP oil is spreading is ongoing, and that other ships have been sent out in the Gulf to take new water samples.

"Those are in the lab being analyzed now," she said. "We will report on those as soon as we can."

Millions of gallons of crude have poured in the Gulf of Mexico since the April 20 explosion on the BP-operated Deepwater Horizon rig, lying just off the Louisiana coast.