A single mother in Florida and her 6-year-old daughter are at the center of a puzzling mystery. Detectives hope the public can help put the pieces together.

Just days before Christmas, a silent night erupts into hellfire. It's a blaze of the cruelest kind. A horrible tragedy, or intentional evil?

Then out of the ashes, a faint sound of hope. Will there be a Christmas miracle?

Christmas in Gainesville, Florida wasn't going to be snowy. But for 6-year-old Kira Radcliffe and her mom Heather, it was still going to be perfect.

Bob Radcliffe says after years of struggling as a single mom, his baby sister Heather was finally on the right path.

"She made sure that Kira had what Kira needed," Bob tells Crime Watch Daily.

Heather was the big boss to a mostly male crew of tree-trimmers for a local company.

"She would complain every once in a while like everybody does about work," said Bob.

Some of the guys didn't like being ordered around by a 28-year-old woman, but Heather was tough on the job and determined to make a better life for little Kira, starting with the holidays.

Heather and Kira had just returned home with their Christmas tree. They need some extra muscle to carry it inside, so they left it strapped to Heather's pickup truck and headed inside with their dog. What happened behind those closed doors over the next eight hours remains a mystery.

"Absolutely no indication that there were problems within her life at all," said Bob.

Around 6:30 in the morning of Dec. 9, 2006, Heather Radcliffe's neighbor spots raging flames shooting out of Heather's roof and calls for help. Heather's sister Maria lives a mile away and woke up to the sirens.

"I knew right there and then that something was wrong and, and I didn't know what it was, but there was a gut feeling," said Maria Radcliffe.

When veteran fire investigator Kelly DeRasmo arrives, she fears that if anyone is still inside, they won't make it out alive. She finds it strange that the fire broke out in the middle of the night, and the front door is unlocked.

"I could still see smoke coming from the attic space, but a huge whole was in that right-above-the-bedroom area," said DeRasmo.

Still, early on everyone believes it's nothing more than a tragic accident.

"The initial belief was that it was potentially an electrical fire," said Bob.

But something wasn't adding up. There was one massive fire, but two ignition points.

"Heather Radcliffe's bedroom was a separately-set fire," said Kelly DeRasmo.

The house is completely gutted. Then a moment of hope.

"I kept hearing a ringing in the living room, it wasn't a smoke detector, wasn't a burglary alarm," said DeRasmo.

DeRasmo stops in her tracks when she hears a faint sound of life coming from the other room.

When firefighters arrive at the small home of Heather Radcliffe and her 6-year-old daughter Kira, they find Heather's truck in the driveway still loaded with a freshly cut Christmas tree. The front door is unlocked and the garage door was open.

Fire investigator Kelly DeRasmo can only hope Heather and little Kira somehow escaped the inferno.

"We had a pretty complex scene," said DeRasmo.

But as the final flame is snuffed out, there's no sign of Heather, Kira or the family dog. At first Heather's brother Bob Radcliffe says the family believes it's simply a tragic but accidental house fire triggered by a faulty ceiling fan.

"I was not suspicious at all," said Bob.

But Inspector DeRasmo knows immediately this was no accident. The fire started in two different spots. The first ignition point was Heather's mattress. The second and more volatile was set in Kira's bedroom.

"Obviously by using an accelerant in conjunction with a cigarette, a match," said DeRasmo.

When firefighters finally enter the house, they hear a faint but familiar noise in the living room.

"I kept hearing like a phone ping," said DeRasmo.

They track the sound, hoping it leads to a Christmas miracle. Instead they find heartbreak.

"I remember seeing Kira's body in near the living room almost like she got surprised, startled. I can see her mother in the west bedroom, the dog in the office with the door closed," said DeRasmo.

And there next to Kira was her mother's phone.

"She was trying to call someone whose phone number she knew," said Bob Radcliffe.

The brave 6-year-old was trying to call for help, but took her last breath before she finished dialing.

"It never went through," said Bob.

Tragically the worst was yet to come.

When Patty Nixon, the Gainesville Police detective on the case, finally gets a close look at Heather and Kira, overwhelming sadness explodes into fury. The mom and daughter didn't die from the fire -- it was something far more evil and intentional. Nixon says Kira and Heather were murdered in the cruelest of ways.

"Heather was shot three times: twice in the head and once in the chest area," said Patty Nixon. "We believe that Heather was possibly sexually assaulted."

"Kira's death was a combination of both the strangulation and the smoke inhalation," said Gainesville Police Det. Martin Honeycutt.

Detective Honeycutt believes the killer attacked Heather and Kira was murdered after jumping out of her bed trying to save her mom.

"Something woke her up and had her come towards mom's room," said Honeycutt.

"She realized that something was wrong and at the age of 6 was still smart enough and brave enough to get out there and try to do something to help her mom," said Bob Radcliffe.

Detectives believe Kira grabbed her mom's phone and tried to call a family friend, but the killer saw her and choked the life out of her before she could press the last number.

"He wanted her dead so she could not be a witness to identifying him," said Patty Nixon. "I don't know how you get there when you're looking in the eyes of a little 6-year-old."

Cops believe the killer left to get gasoline, then returned and torched the evidence.

"I can't even today be able to imagine why someone or how somebody could do such a terrible thing," said Bob. "The rage, the person became a monster at that point in time."

But finding this monster proves to be a daunting task for Gainesville Police.

"There was about a little over six hours of a time frame that we don't know what occurred within the house," said Honeycutt.

And unfortunately all the fingerprints burned away and any DNA went up in flames.

"I do think the fire complicated the case," said Nixon. "So you have to go back to old-school policing and you really have to just start knocking on doors."

Police wonder if the young mom actually knew her killer and willingly opened the door.

"I don't know why but I do believe this person came in by invitation," said Det. Honeycutt.

There was something else gnawing at cops.

"The dog's location within the house when the dog died was something that led me to believe this person was in the residence by invitation," said Honeycutt.

Normally Heather let the dog run free inside the house, and only shut the dog in the office if company was coming over.

So who was Heather Radcliffe expecting?

"I can't think of anybody that would have wanted to harm either of them," said Bob Radcliffe.

Gainesville Police question Kira's father, but he has a verified alibi. They even dig up old boyfriends.

"Romantic relationships don't always end fairy tale," said Patty Nixon.

But cops can't help but wonder if this was a workplace vendetta.

"She was a very friendly person, but not everybody loves the boss," said Nixon.

Heather managed a crew of mostly male tree-trimmers. Maybe someone got fed up taking orders from a 28-year-old female boss?

"Heather was a forceful individual and wasn't afraid to tell an individual that they weren't doing it correctly," said Martin Honeycutt.

Still, cops can't tie a single person to the murders.

"There has not at this time been enough evidence to convict anybody," said Nixon. "Are there working suspects? Sure, but conviction is a whole 'nother ball game."

Now Heather and Kira's family and the Gainseville Police Dept. need the public's help to catch the killer or killers.

Contact Alachua County Crime Stoppers at (352) 372-7867, or submit an anonymous tip to Crime Watch Daily.