The truth might have surfaced sooner if Williams were white or Latino instead of African-American.
There's no way to know for sure, of course, but data about wrongful convictions show that blacks who are exonerated after a bogus conviction have served 12.68 years on average before the good news, according to Pamela Perez, professor of biostatistics at Loma Linda University. It takes just 9.4 years for whites and 7.87 for Latinos.
There's enough of a pattern that the differences between racial groups cannot be called random, Perez said. But there isn't enough information to explain what caused the differences.
"All we can do is infer," Perez told HuffPost. "You can't prove a darn thing."
She discovered the different timespans by examining 1,450 exonerations listed on the National Registry of Exonerations through Oct. 20, 2014. Perez conducted the research for , a consumer research group.