UPDATE April 10, 2018 2:24 p.m. PT: The Scottsdale Police Department announced an arrest has been made in the 2015 murder of Allison Feldman.

At a 4 p.m. PT news conference on Tuesday, April 10, police announced Ian Mitcham was arrested Tuesday and charged with first-degree murder. Mitcham was currently in custody and was being interrogated.

Scottsdale Police found unknown DNA at the Feldman’s murder scene. That sample was identified through a familial DNA search to a suspect already in custody, which led to Mitcham’s arrest.

Police said they have not connected a link between Mitcham and Feldman.

Allison Feldman didn't have enemies.

"Allison was a big supporter of the Arizona Burn Foundation Camp Courage, a camp for kids that are severely burned and she would go up there every summer on her birthday usually and work in the infirmary and help these kids," said Harley Feldman.

"It was a huge part of her life. Something she was so proud to be involved with," said Allison's sister Kelly Weinblatt.

At 31 years old, Allison, a Scottsdale, Arizona medical sales representative, had a lot to be proud of.

She had just been promoted at work and recently bought her first house. She was just weeks away from getting engaged to her longtime boyfriend Alex.

"She was really at the prime of her life," said Alex.

Then, February 17, 2015, a Tuesday: According to police records, Allison arrived home right around 7:15 p.m. After that came the usual round of calls.

"I was actually the last person to speak with her," said sister Kelly. "We talked about nothing important, just girly dumb stuff. And then unfortunately I had to cut the conversation short."

The next day, friends and family go about their normal routines, with one noticeable exception: No calls from Allison.

"On Wednesday several of us tried to call her and her phone was off, and being in sales she never turned her phone off," said Harley Feldman.

"My thought was she's on a plane, she's in the hospital where she doesn't get reception," said Kelly. "My dad said 'Well her phone has been off all day' and I immediately knew something was wrong."

Allison's dad asks police to go by the house for a wellness check. What he didn't yet realize was they were already there.

"Her boyfriend had gone over," said Harley. "I didn't know he was on the way but he had gone over around 4 in the afternoon."

What he found would change the lives of all who knew her forever. Allison Feldman was found dead, lying naked in a pool of her own blood.

"We initially responded to the home on Wednesday, February 18th," said Scottsdale Police Detective Brian McWilliams.

"The police called about 7:00 and he said to me it sounds like you're driving and I said I am and he said would you mind pulling off the road and I already knew what he was going to say. And it was pretty hard to hear."

Allison's own mother, Elaine, was on the other side of the country when news broke.

Though police release few details about exactly how Allison was killed, or what might have happened leading up to it, it has been reported that she suffered severe head trauma.

"They struggled we know that," said Harley. "Who knows what happened after that."

"When the first-responders entered the residence they were overpowered by a strong bleach-like smell," said McWilliams.

Whoever was there attempted to clean up. But why?

Was it a home invasion gone wrong? Police did find some of Allison's items missing, including jewelry, credit cards, and that daily connection to her family -- her phone.

"However, we also did find some other valuables in the home that were in plain view that were not taken," said Det. McWilliams. "There were no signs of forced entry. During that search in the home is when we found the home security system.

"The security system records the activity anytime a window is open or closed," said McWilliams. "We know that there was a door open when the killer left the residence at approximately 1 a.m."

So then what happened during those five hours between when her sister last talked to her, and the suspected killer left her home? The crime seemed too up-close and personal to be random.

Right away, police look at the man who found Allison dead, her fiancé-to-be, Alex.

"He was completely cooperative," said McWilliams. "We've interviewed him several times in reference to this case. In addition he consented to a forensic nurse exam and he has since provided his fingerprints and DNA for comparison and analysis. He has cooperated with us throughout the entire investigation."

A dead end. Then police announce what seems like a major breakthrough.

"We recovered several DNA samples from who we believe is the suspect," said McWilliams.

In addition, detectives find fingerprints they believe belong to the killer. Unfortunately, they lead nowhere.

"The DNA was submitted to CODIS, which is a national database. To date we have not received a hit or a match," said McWilliams.

As weeks turn to months, authorities come to a disturbing conclusion.

"It appears that this was a random act of violence," said McWilliams. "We've not found anything that lead us to believe that Allison knew her killer."

"I believe Allison was targeted by someone," said her father Harley. "I don't believe she knew this person, but that he knew who she was."

That's a theory police have not ruled out.

"The home is situated with an alley to the rear and it does have a low block wall," said McWilliams. "The killer could have accessed the residence from the alley into the back yard."

"I don't know that he came in to murder her," said Harley. "But I know that once he entered her house bad things can happen."

Scottsdale Police have brought in help from the FBI, in addition to other investigative units, and authorities are entertaining a theory that the murderer may have been a visitor from out of town.

"The killer would've been in Scottsdale between February 17th and February 18th of 2015, approximately 8 p.m. to 1 a.m. It is possible that the killer sustained cuts or bruises during the struggle within the home and during the attacks," said McWilliams.

For now, loved ones have only their memories and unanswered questions.

Allison's family and police are hoping a $10,000 reward will help someone come forward with information that will lead to the arrest of her killer.

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