Not according to the article. They had someone whose fingerprints did not match, but they arrested him anyway.
Specifically, the unusual similarity between Mayfield's fingerprint and the fingerprint on a bag of detonators found in Madrid confused several fingerprint experts. FBI laboratory examiners identified Mayfield's fingerprint as matching a print found on a bag of detonators connected to the Madrid commuter train attack, which killed 191 people and injured almost 1,500. A court-appointed fingerprint expert also misidentified the prints.
The misidentification wasn't found until later. When he was arrested, it was in part because they believed they had a matching fingerprint. He was not arrested in spite of some knowledge that fingerprints didn't match.