Scientists from the University of South Florida announced on Friday that they have “definitively connected” the underwater oil plumes to BP’s ruptured—and still slightly leaking—well in the Gulf.

Last month, the National Oceanic and Atmospheric Administration confirmed that the oil plumes were from BP’s well. At the time, that conclusion was based on what the agency called a “preponderance of evidence,” but no chemical fingerprinting of samples had yet conclusively determined origin.

A team of Florida scientists was trying to perform the chemical fingerprinting, but as we noted, BP had initially refused to provide it with samples of oil from its well. After several Florida lawmakers intervened, BP representatives said the scientists would receive their samples, and three weeks later, the company handed them over.

One of the scientists, chemical oceanographer David Hollander, called the spill a “three-dimensional catastrophe.” Hollander had earlier called BP’s refusal to provide samples “a little unsettling.”

NOAA also released a new analysis of the subsea oil. That analysis confirmed that the “subsurface oil concentrations are highest near the wellhead and become more diffuse farther away from the source,” and that areas of lower oxygen readings are also where concentrations of oil are elevated.

According to NOAA, this could be due to oil- and methane-eating microbes that deplete oxygen in the water—potentially exacerbating the Gulf’s “dead zones.”

One marine sciences professor told McClatchy Newspapers last week that these microbes have grown “surprisingly fast” within oil plumes.