PHOENIX - Sammantha Allen now joins a small group of women across the country currently serving a death sentence.

"There are approximately 2,900 people on death row across the United States," said Robert Dunham, the executive director of the Death Penalty Information Center. "Of those, 55 are women."

The center is a national non-partisan, non-profit studying the issue of death penalties. Dunham has no ties to Allen's case and explains women receiving a death row sentence is pretty rare, but typically defendants have certain things in common.

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"It is almost universally the case that they've received chronic lifelong trauma," he said.

A death sentence doesn't always mean the defendant will be executed and Dunham said these situations are typically argued in court with cases eventually overturned.

If those attempts are unsuccessful, it can take, on average according to the center, anywhere from 15 to 18 years before an execution will take place.

"It's supposed to be imposed for the worst of the worst, but is it in fact imposed for the worst of the worst?" Dunham says.

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Critics of the death penalty question whether jurors and judges impose it consistently and fairly every single time.

Dunham's research suggests due to the severity of these crimes, jurors may have challenges separating their emotions from the facts of the case.

"It's so emotional and so painful, the evidence, and jurors can be blinded by that and not look at the underlying question of what did the defendant actually intend to do?" Dunham said.