Courtesy of the Center on Wrongful Convictions Nicole Harris was exonerated in 2013 in the death of her four-year-old son.

Nicole Harris lost her 4-year-old son in a tragic accident, then spent nearly eight years behind bars after being found guilty for his death.

Last June, prosecutors dismissed the charges against the Chicago mother after a new trial determined Jaquari's death was accidental.

Harris was one of 87 people exonerated in 2013, a record-breaking year for official vindications in the United States, according to a new report from the National Registry of Exonerations. Nearly a third were in cases where no crime occurred — such as Harris'.

Harris' son, Jaquari, died in 2005 after an elastic band from a fitted bed sheet asphyxiated him. Harris was questioned by police for 27 hours after the boy died. She said she eventually gave a videotaped confession because she was threatened and denied basic necessities, like water, food and bathroom breaks, during her interrogation.

Jaquari's older brother had seen him wrap the band around his neck while he was playing, but because he was only 6 when Jaquari died, a trial judge at the time found him incompetent to testify at the time.

Harris is just one of eight female prisoners who was exonerated last year. The majority of exonerees — individuals who were convicted and later relieved of all the legal consequences — were male, and more than half of them were black.

One exoneree, Missouri inmate Reginald Griffin, had been sentenced to death before his name was cleared.

The earliest cases in the National Registry of Exonerations' database date back to 1989 — when DNA evidence freed its first two prisoners. There are a total of nearly 1,300 exonerations in the registry from 1989 through January 2014, all of which are listed on ExonerationRegistry.org, a joint project between Michigan Law and Northwestern Law.

The increase in exonerations is positive news, said Michigan Law professor Samuel Gross, editor of the registry and an author of the report, but it doesn't necessarily mean innocent defendants are spending less time behind bars.

"It says that we've been doing a better job of discovering and remedying [wrongful convictions]," he said. "It doesn't tell us about the underlying rate of wrongful convictions, in particular because these weren't wrongful convictions that happened last year or the year before. The average time to exoneration for these cases was over 12 years."

A handful of efforts to reverse convictions have made headlines lately, including the case of a 14-year-old boy who was executed in South Carolina for allegedly killing two girls in 1944. Advocates argue George Junius Stinney Jr., who was black, was unfairly convicted in the murder of the white girls, and have been pushing for the state to grant him a new trial, seven decades after he was sent to the electric chair.

There are no statistics on how many of the 2.3 million people who are currently in custody in the U.S. might be imprisoned for false convictions, but estimates based on various prison populations suggest the rate ranges from 2.3 percent to 5 percent, Gross said.

For innocent people who get exonerated, life isn't always easy after serving time.

"People will shy away from you," Gross said. "They've lost 10 years, or in some cases, 30-some years of their life. Their children have grown up if they had children, their spouse may have left them, their parents may have died, they have no skills. For many people, the destruction that has occurred is irreparable."

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