Home Alone

Episode of 20/20 · October 3, 2026 · 1 h 26 min

John Quiñones reports on the 2015 murder of Allison Feldman in Scottsdale, solved through Arizona's first use of familial DNA and contested in court.

Summary

This 20/20 episode, reported by John Quiñones, examined the February 17, 2015 murder of 31-year-old Allison Feldman, a medical sales representative found beaten, strangled and sexually assaulted in her Scottsdale, Arizona home by her boyfriend Alex Stone. Scottsdale detectives John Heinzelman and Hugh Lockerbie described a bleach-scented crime scene, signs of a struggle, and a brown stain labeled PMH that yielded an unknown male DNA profile also found on a beer bottle and door handles.

The DNA eliminated Stone, Allison's boss Jeff Ciardi, and more than 130 other people, and produced no hit in CODIS, leaving the case cold. A chance meeting between Allison's mother and former Arizona state senator Barbara Leff on a 2016 trip led the state to authorize familial DNA searching for the first time. In 2018 it pointed to convicted sex offender Mark Mitchum, whose brother Ian Mitchum's retained DUI blood sample produced a full match.

Mitchum was charged in 2018, but a county judge suppressed the DNA because his blood was supposed to have been destroyed; the ruling was reversed on appeal and upheld by the Arizona Supreme Court in 2024. At trial the defense argued DNA can transfer innocently and pointed to pharmacist James Katsoulamidis, who had allegedly joked about killing Allison but was cleared by DNA. The jury convicted Mitchum of murder, sexual assault and burglary but deadlocked on the death penalty, with a new sentencing trial expected in 2027. Harley Feldman, Allison's father, died a week after delivering his victim impact statement.

Chapters

1:55
Who Allison Feldman was
Family and friends describe Allison Feldman's life in Scottsdale, her career, her volunteer work with burned children, and her relationship with Alex Stone.
Linked moment · 7:24Skip to 7:24 using a listen link in the info box.
7:24
Disappearance and discovery
After Allison stopped answering messages, her boyfriend Alex Stone entered her home and found her dead, calling 911.
10:35
The crime scene
Investigators describe the bleach smell, signs of a violent struggle, evidence in the pool, a broken beer bottle, and a likely entry through the back alley.
16:51
The boyfriend under scrutiny
Detectives interviewed Alex Stone and collected his DNA as a routine first suspect.
23:57
The PMH stain and unknown DNA
A tobacco-like stain yielded an unknown male DNA profile found in four places that excluded Stone and had no CODIS hit.
27:01
A widening net
Police interviewed hundreds and collected DNA from over 130 people, including Allison's boss and a man linked by a fingerprint, without a match.
34:52
Persons of interest and a cold case
Tips about neighbor Alex DeLucio and veteran Christopher Haight led to DNA exclusions as the case went cold.
44:03
Familial DNA comes to Arizona
A meeting with former state senator Barbara Leff led Arizona to permit familial DNA searching, which pointed to the Mitchum family in 2018.
52:19
The match and the arrest
A retained DUI blood sample matched Ian Mitchum, who denied ever being in the house and was charged with first-degree murder.
55:30
Battle over the DNA evidence
The DNA was suppressed by a county judge, reinstated on appeal, and upheld by the Arizona Supreme Court in 2024.
1:02:58
The pharmacist
Pharmacist James Katsoulamidis, cleared twice by DNA, had allegedly joked to neighbors about killing Allison, setting up the defense's alternate-suspect theory.
1:08:13
The trial
Prosecutors relied on DNA, choking testimony, and a cash deposit, while the defense argued DNA transfer and blamed Katsoulamidis.
1:22:09
Verdict and aftermath
Mitchum was found guilty, Harley Feldman died a week after his victim impact statement, and the family remembered Allison.

Key points

What was said, by whom, with the exact words. Timestamps jump to the moment.

Hugh Lockerbie
Lockerbie said that on arrival the scene smelled overwhelmingly of bleach and the attack appeared to be a blitz attack.
“It looks like it was a blitz attack, like she wasn't expecting this attack from this individual”
Listen from 11:27 · Murder of Allison Feldman
John Heinzelman
Heinzelman said a witness's report of a scream put the murder around 9:30 p.m., and door records showed the killer left at 1:04 a.m.
“Based on a witness that heard a scream sometime around 9.30, that Tuesday evening is when I believe the murder occurred”
Listen from 15:24 · Murder of Allison Feldman
John Heinzelman
Heinzelman described the PMH stain on the dining room floor as the item that stood out from everything else at the scene.
“It was the sore thumb that sticks out amongst everything else”
Listen from 24:26 · DNA evidence
John Heinzelman
Heinzelman said the lack of a CODIS hit indicated the killer had never been arrested and was not in the system.
“It tells us that this person has never been arrested, that this person is not in the system”
Listen from 26:46 · Combined DNA Index System
John Heinzelman
Heinzelman called Arizona's first use of familial DNA in the Feldman case groundbreaking.
“Allison's case is the very first case in Arizona where familial DNA was used”
Listen from 47:59 · Familial DNA searching
John Heinzelman
Heinzelman said the test of Ian Mitchum's retained blood sample was a full match to the PMH stain and all scene DNA.
“This is a 100% match to our PMH, to all the DNA in the scene”
Listen from 52:27 · DNA evidence
Hugh Lockerbie
Lockerbie said Mitchum did not deny the DNA was his but denied entering the home and could not explain how it got there.
“He did not deny that DNA being his, but he did deny entering in the home”
Listen from 57:16 · State of Arizona v. Ian Mitchum
Ashley Holden
Holden explained that the defense argued the retained blood sample violated Mitchum's constitutional rights and expectation of privacy.
“So the defense said this violates his constitutional rights, his expectation of privacy, and it should not be allowed in at trial”
Listen from 59:00 · Arizona Supreme Court DNA suppression ruling
John Heinzelman
Heinzelman characterized the defense's focus on the pharmacist as the familiar 'some other dude did it' strategy.
“The defense always has this, what we call the Saudi defense. Some other dude did it”
Listen from 1:16:32 · State of Arizona v. Ian Mitchum

People

In the conversation

John QuiñonesABC News correspondent who reported and narrated the episode
Deborah RobertsABC News correspondent and 20/20 co-anchor who conducted the episode's interviews
David MuirABC News anchor and 20/20 co-anchor
John HeinzelmanScottsdale Police Department detective who led the Feldman murder investigation
Ashley HoldenInvestigative reporter at ABC15 in Phoenix who covered the case
KellyOlder sister of murder victim Allison Feldman
Hugh LockerbieScottsdale Police Department lieutenant and early investigator on the scene
Harley FeldmanFather of Allison Feldman, who pushed for the case to be solved
Jeff CiardiAllison Feldman's boss and mentor at her medical supply sales job

Discussed

Allison Feldman31-year-old Scottsdale medical sales representative murdered in her home in February 2015
Ian MitchumScottsdale-area man convicted in 2026 of Allison Feldman's murder, sexual assault and burglary
Alex StoneAllison Feldman's boyfriend who found her body and was cleared by DNA
James KatsoulamidisPharmacist and neighbor whom the defense presented as an alternate suspect; cleared by DNA
Barbara LeffFormer Arizona state senator who helped bring familial DNA searching to Arizona
Mark MitchumIan Mitchum's brother, a convicted sex offender whose DNA produced the familial lead
Elaine FeldmanAllison Feldman's mother
Christopher HaightIraq War veteran reported by his mother as a person of interest, later cleared
Alex DeLucioNeighbor named in an anonymous tip and cleared via surreptitiously collected DNA

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From the publisher

A young woman is murdered in her own home, leaving only one mysterious clue to help catch a killer. John Quiñones investigates this heart pounding, incredible story. To get ad-free episodes, early access to new true crime podcasts, and exclusive bonus episodes, subscribe to 20/20 True Crime+ on Apple Podcasts. ⁠Click here⁠ to start your free trial today. Terms apply. Learn more about your ad choices. Visit podcastchoices.com/adchoices

Summary, chapters and key points were generated from the episode transcript on October 5, 2026. Quotes are checked word for word against the transcript.

Categories: True Crime