The Rare Genetic Disorder That Put Melissa Lucio on Death Row

Junk science helped put a Texas mother on death row. Could real science set her free?

Melissa Lucio

It’s not unusual for a death row inmate to maintain their innocence. While a wrongful execution throws the barbarity of the death penalty into the starkest relief, they’re not necessary to make that argument, and beyond an obligatory mention I usually leave innocence claims to the plethora of attorneys willing and far more able to discuss them. The argument from Texas’s Melissa Lucio, however, is unlike any other I’ve seen in the short time I’ve been covering capital punishment: she’s not just claiming that she didn’t commit the crime but that it didn’t happen.

Lucio called 911 after she found her daughter Mariah Alvarez unresponsive and not breathing on February 12th, 2007. Mariah was her 12th child of 14, and she had only recently regained custody of her younger children a few months earlier after a battle with cocaine addiction. Prosecutors suspected Mariah, who was missing hair, had a broken arm, and displayed what appeared to be a bite mark on her back, had died as the result of Lucio’s abuse. While Lucio maintained at trial that Mariah died following a fall down the stairs (to which two of her children attested in police interviews¹), she initially confessed—after maintaining her innocence more than 100 times—at the end of a “marathon” five-hour interrogation in which she was held without food, water or counsel despite grieving one child and being pregnant with two others.

Known police and prosecutorial misconduct abound in the case, which I will again leave to better-situated analysts. The question of the alleged bite mark, however, concerns a deeply fascinating, troubling medical question: attorneys for Lucio filed new evidence in 2022 suggesting that a little-known blood clotting disorder known as disseminated intravascular coagulation may be responsible for one of the signs of abuse Texas prosecutors relied on to send her to death row in 2008.

How A Clotting Disorder May Have Changed the Case
Normally, blood clotting (or coagulation) comes via one of two common pathways, commonly known as the coagulation cascade. YouTube continuing education creator Rhesus Medicine describes the coagulation cascade as “something you’ll learn, forget, and re-learn“ if you take up a career in healthcare; the important bit to understand for our purposes is that it works by “Factors” being activated when the body senses it is bleeding. In the extrinsic pathway through the cascade (the one activated by an injury), Tissue Factor activates the remaining factors along the cascade to produce prothrombin, thrombin and then fibrin, which ultimately forms a clot. If an injury results in damage to vascular cells without producing significant bleeding, however, Tissue Factor may be released, resulting in fibrin being released and clots being formed with no bleeding to stop. These clots then travel around the body, often manifesting as injuries that often resemble bite marks.

An advanced case of non-traumatic DIC, courtesy of Emergency Medical Minute.

Since a significant amount of blood flows to the head (as any experienced parent, let alone paramedic, can tell you), severe traumatic brain injuries like Mariah Lucio’s are especially susceptible to DIC.

A clot without a bleed is also extremely and suddenly deadly. If a clot has nowhere to go, it can travel throughout the body until it gets stuck somewhere. A clot in the circulation between the heart and lungs can feel like a relatively benign breathing issue that rapidly develops into cardiac arrest, with a survival rate of 5%. Mild traumatic brain injuries still pose a significant likelihood of developing coagulopathy, raising the likelihood that Mariah suffered an eventually fatal fall and appeared well enough not to need assistance.

Jurors Heard None of This
At the time, however, Melissa Lucio’s jurors didn’t hear any of this. Instead, they heard Lucio coerced into saying “I’m responsible“ for the supposed bite mark, and the trial included “definitive“ testimony from a “bite mark analyst.” (Friend of the Project Radley Balko describes the near-unanimous scientific disregard for bite mark analysis succinctly at “The Watch“ and expansively in his The Cadaver King and the Country Dentist.)

This case, however, offers a rare reason for optimism in death penalty chronicles. A Texas court stayed Lucio’s execution just 48 hours before her scheduled date in 2022, and hasn’t ordered a new one. Then last week, another court recommended overturning her conviction based on the suppression of her children’s testimony. If she is granted a new trial, medical evidence can at least counter the state’s potential to reintroduce bite mark analysis (despite recommendations by a Texas scientific panel, it’s still admissible there). It’s hard to hold a lot of hope this will mean much against the increasingly relentless tide of state killing, but it’s also hard to discard the poetry in modern science thwarting our ancient desire for retribution, even just this once.

1. For the record, Lucio’s fifth child Selina, by contrast, believes she is guilty and would eventually claim on TikTok to at least be aware of instances of Lucio’s physical abuse of Mariah.