How Two Citizen Sleuths Spent Decades Trying to Solve the Double Homicide of A Killer Story

Keen and Eileen Umbehr in A Killer Story —Courtesy of HBO The tip came in 2017 from Alma, Kansas, from a stay-at-home mother.

Eileen Umbehr asked whether Joe Sexton, a veteran investigative journalist who worked at The New York Times and ProPublica , wanted to know the truth about a double homicide in Topeka.

Karen Harkness, daughter of a bigtime Topeka businessman, and her boyfriend Mike Sisco, a divorced father of two kids, were murdered on July 7, 2002, in the middle of the night, and authorities were convinced that Sisco’s ex-wife Dana Chandler was the killer.

She was arrested, tried, and convicted of first-degree murder.

Sexton, who thought the case was closed, emailed Umbehr back a polite “thanks, but no thanks.” Umbehr kept writing Sexton, anyway.

Some weeks brought 10 emails, then none for two, then 25 in a single day, packed with court records, ballistics reports, property filings.

Her correspondence grew from hundreds to thousands of letters.

Sexton wasn’t sure whether to call the police on Eileen or hire her for her thoroughness.

But he gave her a nickname: “pen pal.” By then, Umbehr and her husband Keen, a lawyer, had spent years working the case and advocating for Chandler at their own expense.

Then came email 2,714.

The Kansas Supreme Court, Umbehr explained, had thrown out Chandler’s murder convictions, a rare occurrence.

Sexton replied in six words: “Perhaps I should come see you.” Those six words began a journey which is now the subject of A Killer Story , a three-part documentary premiering Sept.

10 on HBO.

Featuring Sexton alongside the married true-crime enthusiasts who recruited him—strangers to Chandler when they took up her case—it unspools the story of the deaths of Sisco and Harkness, and the case against Chandler, who was convicted in 2012, granted a new trial in 2018, retried to a hung jury in 2022, and convicted again in 2025.