The Matamoros Devil Murders (Part 2)

Episode of Morbid · May 25, 2026 · 55 min

Ash Kelley and Alaina Urquhart conclude the story of Mark Kilroy's 1989 murder by Adolfo Constanzo's drug-smuggling cult near Matamoros, Mexico.

Summary

In the second and final part of their coverage, Morbid hosts Ash Kelley and Alaina Urquhart opened with banter and promotion of Urquhart's forthcoming novel The Butcher Legacy and an upcoming June 27 live show at Radio City Music Hall.

Kelley then recounted the confession of Serafín Hernández, who admitted that the Hernández gang, operating under Adolfo Constanzo, known as El Padrino, had abducted University of Texas student Mark Kilroy in Matamoros to serve as a ritual sacrifice. She described Kilroy's torture and murder, the exhumation of 14 bodies from the ranch, the involvement of anthropologist Anthony Zavaleta, and the ritual cleansing of the property by a curandero before the investigation resumed. She also traced Constanzo's upbringing in Miami, his fortune-telling and curse-selling business in Mexico City, and the recruitment of college student Sara Aldrete as his high priestess.

The episode covered the manhunt that ended on May 6, 1989, in Mexico City, when Constanzo ordered follower Álvaro de León Valdez to shoot him and Martín Quintana Rodríguez, and the subsequent convictions and sentences of cult members. The hosts praised the Kilroy family for establishing the Mark Kilroy Foundation, which works to prevent substance abuse among young people, and urged listeners to remain wary of strangers. They closed with a fun fact about sharks predating trees.

Chapters

0:00
Opening banter
The hosts chat about lunch, spicy food and chewy Tums.
2:43
The Butcher Legacy plug
Urquhart and Kelley promote the third Butcher novel, set in New Orleans at Halloween, and discuss its characters.
6:18
Radio City show announcement
The hosts promote their June 27 Radio City Music Hall show with a special guest and custom Romanian dresses.
7:57
Serafín Hernández confesses
Kelley recounts the interrogation in which Serafín Hernández admitted the gang murdered Mark Kilroy as a sacrifice under Adolfo Constanzo.
15:30
The abduction and murder of Mark Kilroy
Kelley describes how Kilroy was kidnapped in Matamoros, held at the ranch and killed in a ritual led by Constanzo.
20:30
Excavating the ranch
Investigators exhume 14 bodies and anthropologist Anthony Zavaleta identifies the practices as a perversion of Palo Mayombe pointing to a Cuban leader.
24:10
Adolfo Constanzo's background
Kelley traces Constanzo's Miami childhood, his mother's influence, and his move into fortune-telling and curses for elites and drug dealers in Mexico City.
33:16
Sara Aldrete and escalating killings
The alliance with Elio Hernández, Sara Aldrete's transformation into high priestess, and increasingly reckless murders including Elio's own nephew are described.
41:19
Cleansing the ranch
Commander Benítez halts the search until a curandero burns the shack and ritually neutralizes the cauldron.
44:35
Manhunt and Constanzo's death
Additional victims are identified and the fugitives are tracked to Mexico City, where Constanzo orders a follower to shoot him during a police standoff.
47:41
Sentences and the Kilroy family's legacy
Kelley details the convictions and sentences, the two suspects still at large, and the founding of the Mark Kilroy Foundation, followed by safety reflections.
51:55
Fun fact and sign-off
Kelley shares that sharks are older than trees and the hosts muse about ocean exploration before signing off.

People

In the conversation

Ash KelleyCo-host of the true crime podcast Morbid
Alaina UrquhartCo-host of Morbid, autopsy technician and author of the Butcher novels

Discussed

Mark KilroyUniversity of Texas student abducted and murdered in Matamoros in 1989
Adolfo ConstanzoCuban-American cult leader known as El Padrino who led the Matamoros ritual killings
Sara AldreteFormer college student who became Constanzo's high priestess and was convicted in the murders
Serafín Hernández GarcíaHernández gang member whose confession revealed the Kilroy murder
Elio HernándezLeader of the Hernández drug organization who allied with Constanzo
Juan Benítez AyalaMexican federal police commander who led the ranch investigation
Anthony ZavaletaAnthropologist and expert in Afro-Caribbean religions who consulted on the case
Álvaro de León ValdezCult member convicted of killing Constanzo and Martín Quintana Rodríguez on Constanzo's orders
Helen KilroyMark Kilroy's mother, co-founder of the Mark Kilroy Foundation
Jim SchutzAuthor who wrote about Constanzo's early life in Miami
Gary CartwrightJournalist who wrote about the cult's victims

Topics

From the publisher

(Part 2 of 2). Visit https://www.markkilroyfoundation.org If you would like to donate to the Mark Kilroy Foundation. In March 1989, twenty-one-year-old University of Texas student Mark Kilroy and some friends traveled south of the border to Matamoros, Mexico to celebrate the end of spring break, along with thousands of other American students that year. After drinking all night at a bar on the night of March 10, Kilroy got separated from his friends when they decided to call it a night a little after 2:00 am. No one would see Mark Kilroy alive again. As one of several towns bordering the United States, Matamoros was popular with American tourists; however, by the late 1980s, it was beginning to develop a reputation for drug-related crime. In fact, Mark Kilroy was just one of sixty people who went missing in Matamoros in just the first three months of 1989 alone. When Kilroy’s friends reported him missing to the Brownsville, Texas police a massive search began, with investigators fearing Mark might have been kidnapped by one of the local gangs. It turned out, the truth was far worse than anyone had feared.

Summary, chapters and key points were generated from the episode transcript on September 28, 2026. Quotes are checked word for word against the transcript.

Categories: True Crime