Laboratory tests show that globs of oil found on two Louisiana beaches after Hurricane Isaac came from the 2010 BP spill.

Tests run by Louisiana State University for state wildlife officials confirmed Thursday that oil found on Elmer’s Island and Grand Isle matched the biological fingerprint of the hundreds of millions of gallons of oil that spewed from BP’s Macondo well.

Oil giant BP PLC had said Wednesday some of the oil exposed by Isaac’s waves was from its spill. The company said it would work to clean it up.

Two other samples collected from another barrier island did not match the signature of oil from the BP well.