A new HBO documentary on former Blooming Prairie resident Lois Riess and the nationwide manhunt that ensued after she murdered two people will air this month.

It delivers the goods in one key respect that the raft of other documentaries on the “Killer Grandma” never have. It features the 62-year-old Riess telling, in her own words, why she did what she did in March and April 2018.

That in itself could be an intriguing draw for area viewers who were shocked by her murders and have always wondered “Why?” It will certainly set this two-part documentary titled “I’m Not a Monster: The Lois Riess Murders” apart from others.

How satisfying viewers will find her explanation and reasons for fatally shooting her husband, David Riess, in Blooming Prairie and, weeks later after fleeing south while stopping at casinos along the way, Pamela Hutchinson in a Fort Myers Beach, Fla., hotel room, is an entirely different matter. The trailer promises to delve into the Gothic nightmare, “a disturbing family history and an addiction to gambling,” that apparently was Riess’ life.

“I’ve never given an interview,” Riess says tearfully in the trailer released by HBO. “I hope this is the right thing to do.

“It was just years and years of abuse,” Riess says, referencing her marriage to David, whose killing led her to be sentenced to life in prison in 2020. “I just snapped.”

The documentary runs Tuesday, Oct. 15, and Wednesday, Oct. 16. Both episodes will be available to stream on Max on Oct. 15.

The docuseries attempts to grapple with the biggest head-scratcher: What made this seemingly sweet 56-year-old grandmother turn into a killer? And it discovers a deeper conundrum at the heart of her crime spree. If the murder of her husband was a spontaneous act, the second one was one of cold-hearted calculation: It was an effort to steal the identity of Hutchinson, who looked like Riess.

In the documentary, directed by Erin Lee Carr, who hails from Minnesota, Riess “admits to killing David, pointing to alleged emotional abuse in the relationship, but is unable to justify her methodical, well-planned crime spree that followed, which included embezzling funds, a second murder of a stranger, identity theft, and a callous, detailed coverup of her crimes,” a press release states.

It also roams over an extended cast of characters that includes former friends and neighbors, family members, journalists, an addiction specialist, law enforcement officers, witnesses who encountered Riess before her arrest, and a possible would-be victim.

Riess was apprehended in South Padre Island, Texas, a month after the nationwide manhunt began in the wake of her husband’s murder. Riess surrendered without resistance. Later, she claimed not to remember many details of her crime spree, but “police have evidence that details her sinister plan.”