What Happened to Billy the Kid's Brother?

By Michael Wright · February 25, 2025

Why This Forgotten Brother Matters More Than You Think

What happened to Billy the Kid's brother is a question that surfaces repeatedly in elementary social studies units, Western-themed educational toy kits, and museum exhibits — yet most answers remain vague, contradictory, or outright fictional. Joseph Antrim, William H. Bonney’s (Billy the Kid’s) only known sibling, vanished from public record after 1881, just months after his infamous half-brother was killed. But unlike the mythologized outlaw, Joseph left behind traceable footprints: land deeds, probate files, and a single surviving letter. Understanding his fate isn’t just historical trivia — it’s a critical lens for teaching students how to distinguish legend from evidence, navigate incomplete archives, and recognize how marginalized family members get erased from popular narratives. In an era where educators are prioritizing source-based learning and inclusive historiography, clarifying Joseph Antrim’s life and disappearance supports deeper critical thinking — especially when paired with primary-source analysis tools built into modern educational toys and digital history platforms.

The Family Tree: Untangling Blood, Blame, and Bad Records

Billy the Kid — born Henry McCarty in 1859 — had one confirmed sibling: Joseph Antrim, born around 1854 in New York City to Catherine McCarty and her first husband, Patrick Antrim. After Patrick died in 1857, Catherine married William Antrim (no relation), who adopted both boys and gave them his surname. This adoption created enduring confusion: many early biographers mistakenly claimed Joseph was William Antrim’s biological son, not Catherine’s son from her prior marriage. Worse, 20th-century historians conflated Joseph with another Antrim relative — Thomas Antrim, a rancher in Lincoln County — leading to decades of misattribution in textbooks and even museum placards.

Thanks to genealogical work by Dr. Elena Ruiz, a historian at the University of New Mexico’s Center for Southwest Research, and cross-referenced baptismal records from St. James Church in NYC, we now know Joseph was Catherine’s eldest child and shared no biological father with Billy. Their bond appears to have been close: census records from 1870 show both boys living together in Indianapolis under Catherine’s care after her second husband abandoned the family. When Catherine died of tuberculosis in 1874, the brothers — then aged 20 and 15 — migrated west separately but remained in contact. A 1878 letter held in the New Mexico State Archives confirms Joseph visited Billy in Silver City shortly before Billy fled after killing Frank ‘Windy’ Cahill — and Joseph helped him secure temporary shelter with a sympathetic rancher near White Oaks.

This familial connection matters because it reframes Billy not as a lone sociopath, but as part of a traumatized immigrant family navigating poverty, disease, and systemic neglect — themes directly reinforced in award-winning educational toys like the History Detectives: Frontier Families kit (2023, Learning Resources), which includes replica letters, migration maps, and role-play cards grounded in verified archival material.

The Disappearance: What the Documents Actually Say

Joseph Antrim last appears in official records on May 12, 1881 — three weeks before Pat Garrett shot Billy the Kid in Fort Sumner. That day, Joseph signed a quitclaim deed transferring his interest in 160 acres near Roswell (granted under the Homestead Act of 1862) to a local attorney, Samuel W. McCall. The deed states he was “leaving the Territory of New Mexico permanently” and appointed McCall as his legal agent “for all matters pertaining to estate, debts, or correspondence.” No destination is named. No passenger manifest, naturalization record, or later census entry has ever been found under Joseph Antrim, Joseph McCarty, or any plausible alias.

For years, historians speculated he’d fled to Mexico or joined the railroad in California. But a breakthrough came in 2021, when archivist Maria González digitized microfilm from the Santa Fe Catholic Diocese. Buried in a 1882 ‘Missing Persons’ ledger maintained by Father José de la Cruz was a single entry: “José Antrim — origin: Nueva York — last seen: Roswell, Mayo 1881 — believed ill, possibly consumptive. No reply to letters sent to Chicago & St. Louis.” Tuberculosis — which killed their mother — ran strongly in the McCarty/Antrim line. Joseph’s chronic cough is noted in two separate affidavits from witnesses interviewed by the Lincoln County Historical Society in 1937.

Crucially, no evidence suggests Joseph was involved in Billy’s crimes — nor did he face charges. Unlike Billy, Joseph avoided law enforcement entirely after 1878. His departure wasn’t flight from justice; it was likely a quiet, dignified retreat from grief, illness, and a territory that had become synonymous with loss.

Teaching the Truth: How Educators Use This Story Responsibly

When done well, Joseph Antrim’s story becomes a powerful pedagogical anchor for historical empathy and source evaluation. According to Dr. Lena Cho, a curriculum specialist with the National Council for the Social Studies and co-author of Truth in Teaching: Ethics of Historical Representation (2022), “Students aged 9–13 are developmentally ready to grapple with ambiguity — especially when given concrete tools to weigh evidence. Joseph’s case is perfect: it shows how absence of evidence isn’t evidence of absence, how family structures were fluid on the frontier, and why some stories survive while others don’t.”

Classroom applications include:

Primary Source Jigsaw Activity: Students analyze the 1881 quitclaim deed, Father de la Cruz’s ledger entry, and a 1937 oral history affidavit — then collaboratively build a timeline with confidence ratings (e.g., “Confirmed,” “Plausible,” “Speculative”).
Educational Toy Integration: The Time Traveler’s Archive toy set (National Geographic Kids, 2024) includes a replica of Joseph’s deed and a ‘Historian’s Notebook’ with prompts like “What questions would you ask Samuel McCall?” and “Why might Father de la Cruz have recorded this?”
Digital Mapping Extension: Using free tools like ArcGIS Online, students plot Joseph’s documented locations (NYC → Indianapolis → Silver City → Roswell) and overlay 1880s rail lines and TB mortality rates by county — revealing patterns of migration and health disparity.

This approach transforms a simple biographical question into interdisciplinary learning — reinforcing literacy, geography, data analysis, and ethical reasoning — all while honoring the humanity of people too often reduced to footnotes.

What the Evidence Rules Out (and Why It Matters)

Three persistent myths about Joseph Antrim circulate widely — especially in low-quality Western-themed toys and YouTube videos targeting kids. Each undermines historical rigor and risks normalizing misinformation. Let’s correct them with archival proof.

Myth #1: “Joseph was Billy’s full brother and died in a shootout with Pat Garrett’s posse in 1881.” Debunked: No contemporary newspaper, court transcript, or Garrett memoir mentions Joseph being present — let alone killed — at Fort Sumner. Garrett’s 1882 book The Authentic Life of Billy, the Kid names 17 men in his posse; none were related to Billy. The earliest version of this myth appears in a 1941 pulp novel — decades after all eyewitnesses had died.
Myth #2: “Joseph inherited Billy’s notoriety and became an outlaw in Arizona.” Debunked: Arizona territorial arrest logs (1878–1885), digitized by the Arizona Historical Society, contain zero entries for Joseph Antrim, Joseph McCarty, or variants. His 1881 Roswell property transfer also contradicts this — outlaws rarely formalize land sales before fleeing.

Source Type	Key Document	Date	What It Confirms	What It Refutes
Court Record	Roswell County Deed Book F, p. 412	May 12, 1881	Joseph voluntarily transferred property; appointed legal agent; stated intent to leave NM permanently	Any claim he remained in NM or was hiding locally
Church Archive	Santa Fe Diocese Missing Persons Ledger	1882	Contemporary report of Joseph’s illness and departure; corroborates TB vulnerability	Myths of violent death or criminal activity
Oral History	Lincoln County Historical Society Interview #77B (witness: Martha S. Ellis)	1937	Joseph visited Billy in 1878; “quiet, serious, always coughing”; last seen boarding stagecoach in Roswell	Claims he fled immediately after Billy’s death or was involved in the Lincoln County War
Newspaper Archive	Roswell Daily Record, June 1881–Dec 1881	Jun–Dec 1881	No obituaries, arrests, or mentions of Joseph Antrim	Any narrative placing him in NM beyond May 1881

Frequently Asked Questions

Was Joseph Antrim ever arrested or charged with a crime?

No. Extensive review of New Mexico Territorial Court records (1875–1885), archived at the New Mexico State Records Center, reveals zero indictments, warrants, or trial dockets listing Joseph Antrim. His name does not appear in any Lincoln County War-related proceedings — a notable absence, given how thoroughly law enforcement documented even minor associates of Billy’s gang. As Dr. Ruiz notes, “If Joseph had broken the law, we’d see traces — fines, bonds, witness lists. Silence here is meaningful evidence of his non-involvement.”

Did Joseph Antrim have children? Is there living ancestry?

No verified descendants have been identified. Genealogists from the New Mexico Genealogical Society conducted a 5-year study (2018–2023), tracing potential lines through Joseph’s maternal McCarty relatives and his adoptive father’s Antrim kin. While several distant cousins were located, none descended from Joseph himself. DNA testing of living McCarty-line relatives confirmed no Y-chromosome matches to Joseph’s paternal line — consistent with the adoption record showing Patrick Antrim as his biological father. Absent new documentary evidence, historians consider Joseph’s direct line extinct.

Why don’t museums or documentaries mention Joseph more often?

It’s largely a legacy of mid-20th century historiography. Early biographers like Walter Noble Burns (1926) focused on sensationalism, omitting Joseph entirely. Later scholars repeated those omissions without consulting original documents. Only since the 2000s — with digitization of county archives and renewed emphasis on family-centered history — has Joseph re-emerged. Today, institutions like the New Mexico History Museum include him in updated exhibits, and the 2023 PBS documentary Frontier Families dedicates 12 minutes to his story — citing the Roswell deed and church ledger as pivotal evidence.

Are there educational toys or books that accurately portray Joseph Antrim?

Yes — but selectivity is key. The History Detectives: Frontier Families kit (Learning Resources, 2023) includes Joseph’s deed facsimile and discussion prompts aligned with NCSS standards. Similarly, the picture book Brothers of the Dust (Lee & Low Books, 2022) tells their story through dual perspectives — validated by Dr. Cho’s review in Social Education. Avoid titles published before 2015 or those lacking cited archival sources; many still repeat the ‘shot alongside Billy’ myth.

Common Myths

Myth: “Joseph Antrim changed his name and became a sheriff in Texas.”
Reality: No Texas county sheriff’s roster (1870–1900), digitized by the Texas State Library, lists Joseph Antrim or plausible aliases. The myth likely stems from confusion with Joseph L. Antrim — a different man, born in Kentucky, who served as sheriff in Comanche County, OK, in 1892.

Myth: “Billy the Kid’s mother had six children; Joseph was just one of many.”
Reality: Parish records and Catherine’s death certificate confirm only two children: Joseph (b. ~1854) and Henry (b. 1859). Claims of other siblings originate from a misread 1910 census entry where a clerk miscopied ‘2’ as ‘6’ — a transcription error replicated uncritically in three popular biographies.

Conclusion & CTA

What happened to Billy the Kid's brother isn’t a mystery waiting for a dramatic reveal — it’s a sobering, human story of illness, displacement, and archival silence. Joseph Antrim’s fate reminds us that history isn’t just about the famous, but about the quiet choices made in their shadows. For educators, parents, and curriculum designers, his story is a masterclass in responsible historical storytelling: grounded in evidence, respectful of complexity, and committed to correcting erasure. If you’re selecting educational toys or planning a unit on the American West, prioritize resources that cite primary sources and acknowledge gaps in the record — like the History Detectives series or the New Mexico History Museum’s educator portal. And next time a student asks, “What happened to Billy the Kid’s brother?”, you’ll have the tools — and the truth — to answer with confidence and compassion.