Title capital punishment (Photo credit: Wikipedia)

By Spencer S. Hsu

An unprecedented federal review of old criminal cases has uncovered as many as 27 death penalty convictions in which FBI forensic experts may have mistakenly linked defendants to crimes with exaggerated scientific testimony, U.S. officials said.

The review led to an 11th-hour stay of execution in Mississippi in May.

It is not known how many of the cases involve errors, how many led to wrongful convictions or how many mistakes may now jeopardize valid convictions. Those questions will be explored as the review continues.

The discovery of the more than two dozen capital cases promises that the examination could become a factor in the debate over the death penalty. Some opponents have long held that the execution of a person confirmed to be innocent would crystallize doubts about capital punishment. But if DNA or other testing confirms all convictions, it would strengthen proponents’ arguments that the system works.

FBI officials discussed the review’s scope as they prepare to disclose its first results later this summer. The death row cases are among the first 120 convictions identified as potentially problematic among more than 21,700 FBI Laboratory files being examined. The review was announced last July by the FBI and the Justice Department, in consultation with the Innocence Project and the National Association of Criminal Defense Lawyers (NACDL).

Read More U.S. reviewing 27 death penalty convictions for FBI forensic testimony errors – The Washington Post.