The woman stared at the home with a sense of deep revulsion, contemplating a small bit of revenge. The act would offer a small bit of closure, a formal ending.

She was about to torch the home where her little girl was held captive, tortured and murdered. Now, she was helping to burn it down, an act that only a parent who has lost a child in such a horrific way in such a horrific place would characterize - oddly - as "bittersweet."

"It's bittersweet because it's the last place Somer was alive - and now it's no longer here," Diena Thompson, Somer's mom, tells HNGN in an exclusive interview.

"As a parent, I have an overwhelming sense I failed because I wasn't able to protect my children," says the woman who finds no relief from unfathomable despair. "You have a child die on your watch - let me know if you can get that out of your head."

THE CRIME

Somer Thompson was a cute, bubbly 7-year-old in October of 2009 when she vanished while walking home from school in her Orange Park, Fla., community.

Investigators would discover that a predator, Jarred Harrell, 29, had lured her inside his home. He molested and then murdered her, placing the girl's petite body into a small container within a dumpster. To him she was like trash, to be used and then callously discarded and wind up in a landfill. That's where her body was found.

Harrell became a focus of the investigation when cops arrested him for possession of child pornography three months after the murder. He had been on their radar as early as two months prior to Somer's disappearance, after his roommates went to police to report the discovery of child porn on his computer. In the interim, because police felt they lacked sufficient evidence to make an arrest, he had the freedom to attack and kill again. Ultimately, he confessed to and was charged with Somer's murder to face the death penalty - something Diena desperately wanted.

"I wanted death, but they (prosecutors) said they didn't know if they could get death," Diena says. "If I didn't agree to a deal, they said they would still offer him a deal. So they did."   

Harrell's life was spared because prosecutors didn't pursue the death penalty. Instead they took the easiest path, accepting his guilty pleas to 59 charges - including being guilty of Somer's abuse and murder and molestation of another young girl. All that put Harrell behind bars for six life sentences without a chance for appeal.

In interviews, Harrell has said he wanted to apologize to Somer's family, but when he had the opportunity during sentencing, he didn't utter a word.

"He was a coward and didn't even look up," Diena says.

BURNING DOWN THE HOUSE

Since Somer's murder, everything has changed, says Diena.

"I don't think people realize how much it effects you. I am about six or seven waist sizes smaller," she says. "It impacts my eating, sleeping, thinking... my relationships. It's hard to trust anyone - because people can keep deep dark secrets."

Another thing that changed was Diena's perspective on the house of horrors on Gano Avenue where her daughter had suffered at the hands of such evil.

Living so nearby it was difficult for Diena to avoid, but she went to great lengths to do so.

"I didn't want to see it or think about it," she says.

Shortly after Somer's murder, the house became vacant because the bank that held the mortgage foreclosed on it. But rather than resell it, the bank donated it to the Somer Thompson Foundation, a group Diena set up in honor of her daughter. 

She could do with it what she wished, sell it for a profit to fund the foundation. Instead, Diena donated the house to the Orange Park Fire Department's Station 19 to use for training new firefighters. And so, on Feb. 12, 2015, Diena helped torch the home.

"'Burn baby burn' is what I chanted," she says.  "I was just concerned with getting that ugly piece of property out of here."

THE LAWSUIT

Now, Diena is embarking on igniting a new fire - trying to make sure Florida holds up to its legal obligation to inform victim's families where the violent criminals who took a piece of their family forever are being jailed or when they are let out.

Harrell will never get out, but she believes state representatives are hiding his whereabouts so she won't try to contact him.

"They have changed his name and won't tell me where he is. I can't find out where he is, and it's not right," says Diena.

HNGN has learned that Diena is now planning a lawsuit. She has teamed up with Jordan Davis' father. Davis was the 17-year-old killed in the case involving Michael Dunn in another infamous Florida murder.

"We are getting ready to sue the department of corrections," she says. "We have the right to know where the monster is - and they won't tell us!"

The department had no comment because the legal action hasn't yet been filed.

THE SOMER THOMPSON FOUNDATION

In the wake of Somer's tragic death, Diena is channeling her energy, most of it born of rage, into the Somer Thompson Foundation - a group aiming to help the families of violent crime victims pay their bills while they search for loved ones and fight for justice.

"When we were looking for Somer, our phones were shut off, our electricity was shut off... because we were spending all of our time looking for Somer [instead of making a living]. It wasn't right, and families shouldn't have to endure this."

Somer was missing for two days - but the search for her killer took months.  

Diena also wants to lobby to change laws in Florida in favor of harsher penalties for sex offenders.

She has already been instrumental in getting "Cherish's Law" passed. That law protects children by assigning harsher penalties to repeat sex offenders. It is named for a girl, Cherish Perrywinkle, 8, who in 2013 was abducted from a department store and then raped and murdered by a sex offender with a previous conviction.

Donald Smith, 56, the man charged in her murder, had a long criminal history of sexually abusing young children. In fact, he had been released from jail just a month before he allegedly killed Cherish.  

"These people can't be 'cured'," says a determined Diena. "It's about time we acknowledge that."

To find out more about the Somer Thompson Foundation, visit www.somerthompsonfoundation.org.

Jon Leiberman is an Emmy award-winning investigative correspondent, host, producer, victim advocate and author. He recently wrote the book "Whitey On Trial," about the mob. In addition to contributing to HNGN, he is a contributor to "Snapped" on Oxygen and various other television shows. Leiberman is a former correspondent for "America's Most Wanted." Follow him on Twitter @reporterjon.