Jefferson County sent more criminal defendants to death row between 2010 and 2015 than almost every other county in the nation.

That's according to a report released last week by Harvard Law's Fair Punishment Project. The report also states that all five of those sentenced to death in Jefferson County during that period were black.

Those numbers landed Alabama's most populous county on the short list of 16 outliers in the group's report "Too Broken to Fix."

"These outlier death penalty counties are defined by a pattern of bad defense lawyering, prosecutorial misconduct and overzealousness, and a legacy of racial bias that calls into question constitutionality of the death penalty," Rob Smith, one of the report's researchers, stated in a press release.

It's a report that Jefferson County's District Attorney Brandon Falls believes is flawed and doesn't address the underlying facts of the cases to explain why the defendants were sentenced to death.

"Educated minds can disagree about the effectiveness and appropriateness of the death penalty," Falls stated in an email to AL.com. "The role of the District Attorney's Office is to protect the citizens of Jefferson County by enforcing the law as set out by the Alabama Legislature, the Alabama appellate courts, and the U.S. Supreme Court, and to do so ethically and without bias toward any individual. This responsibility is and always will be the highest priority of my office."

The first part of the report was issued in August and included a look at eight counties, including Mobile County. The second half of the report with the other eight, including Jefferson County, was released last week.

Nationwide, the report states, juries in 2015 returned 49 death sentences, which is the fewest number since the death penalty was reinstated in 1976. That came from 33 counties in 14 states, according to the report. Thirty one states still have the death penalty.

But 16 counties were "outliers," imposing five or more death sentences between 2010 and 2015, the report states. Among these "outliers", two were in Alabama (Jefferson and Mobile) and four in Florida.

Meanwhile Alabama's reputation as being an outlier state when it comes to the death penalty also grew last week.

Florida and Alabama were the only two states that permitted a split jury to recommend death, the report noted. But that changed Friday when the Florida Supreme Court ruled that non-unanimous jury death recommendations are unconstitutional.

That now leaves Alabama as the only state to allow a jury to recommend the death penalty for a defendant on a non-unanimous vote - at least 10 of 12 jurors have to vote for death.

Alabama also finds itself alone in allowing judges to override jury recommendations of life without parole and single-handedly increase the sentence to death. Florida's override law was declared unconstitutional early this year. Delaware had been the only other state to allow judicial override (although judges there didn't use it) but that state's supreme court in August also declared override unconstitutional.

Of the remaining 10 counties in the report's top 16, five are in Southern California, two in Texas, and one each in Louisiana, Nevada, and Arizona.

The report also found that:

Ten of the 16 counties had at least one person released from death row since 1976. -- The 10 counties account for more than 10 percent of all death row exonerations nationwide.

Jefferson had three men taken off death row in that period -

Jefferson County imposes about 1.47 death sentences per 100 homicides.

All five of the cases in Jefferson County between 2010 and 2015 had non-unanimous jury recommendations on what the defendants' sentences should be. Two had their jury recommendations for life without parole overridden to death by a judge. And a third - 33 percent - of the cases had defendants with intellectual disability, severe mental illness, or brain damage.

"The study does not address the facts of any of those cases, but those facts are worth noting for a better perspective of why they received that sentence," Falls said.

The report doesn't also consider the sheer volume of homicide cases in Jefferson County.

Falls notes that during that six-year period of 2010 to 2015 the report studied, there were 180 capital murder cases and 205 Murder cases charged in Jefferson County.

The report doesn't name the defendants in the five cases it reviewed for its report, but according to project officials the five death sentences imposed between 2010 and 2015 in Jefferson County are:

Jeffery Tyrone Riggs

Justin White

Anthony Lane

Dontae Callen

Marcus Benn

The report also reviewed 18 capital murder cases that were decided on direct appeal from Jefferson County - including both Birmingham and Bessemer divisions - from 2006 to 2015.

Of those 18 cases, 89 percent involved black defendants. And six of the cases involved defendants with serious mental illnesses, brain damage, or intellectual impairment, including the case of former death row inmate Esaw Jackson, who was resentenced to life without parole in 2012 for the 2006 shooting deaths of two. The judge found Jackson had an IQ score of 56 and could not be executed.

Fifty-six percent of the 400 cases it looked at in the 16 counties nationwide in the study involved defendants with significant mental impairments or other forms of mitigation, such as the defendant's young age.

"It has become clear that a significant proportion of individuals we are sending to death row suffer from serious mental impairments, or are so young in age, that they appear to be nearly indistinguishable from the categories of people whom the Supreme Court has said we shouldn't be executing due to their diminished culpability," said Carol S. Steiker, Professor of Law at Harvard.