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Murder, She Told

Dark History: The Case of Margaret "Peggy" Mortimer

Murder, She Told

Kristen Seavey

Society & Culture, Documentary, True Crime

4.81.5K Ratings

🗓️ 11 February 2026

⏱️ 58 minutes

🧾️ Download transcript

Summary

1937 - Mexico, Missouri On the eve of Thanksgiving in 1937, 46-year-old Margaret Mortimer, who went by Peggy, was just steps from her front door when she was attacked and killed by an unknown assailant. Investigators found few clues and no obvious suspects, despite a city-wide manhunt. And as early leads faded, local police turned to Ira Cooper, the St. Louis Police Department’s first Black lieutenant, hoping his sterling reputation could bring answers to a case already slipping away. The murder shocked the industrial town of Mexico, Missouri. Peggy was well known and widely liked, with no clear enemies. But on that cold November night, someone was waiting—and the question remains: who? Episode sources and photos: https://www.murdershetold.com/episodes/margaret-peggy-mortimer Support the show: ⁠⁠⁠⁠⁠⁠https://www.murdershetold.com/support⁠⁠⁠⁠⁠⁠ Instagram: ⁠⁠⁠⁠⁠⁠⁠⁠@murdershetoldpodcast⁠⁠⁠⁠⁠⁠⁠⁠ TikTok: ⁠⁠⁠⁠⁠⁠⁠⁠@murdershetold⁠⁠⁠⁠⁠⁠⁠⁠ Facebook: ⁠⁠⁠⁠⁠⁠⁠⁠/mstpodcast⁠⁠⁠⁠⁠⁠⁠⁠ Website: ⁠⁠⁠⁠⁠⁠⁠⁠murdershetold.com⁠⁠⁠⁠⁠⁠⁠⁠ ---- Learn more about your ad choices. Visit podcastchoices.com/adchoices

Transcript

Click on a timestamp to play from that location

0:00.0

On the eve of Thanksgiving in 1937, 46-year-old Margaret Mortimer, who went by Peggy,

0:07.2

was just steps from her front door when she was attacked and killed by an unknown assailant.

0:12.8

The murder shocked to the industrial town of Mexico, Missouri.

0:16.4

Peggy was well-known and widely liked, with no clear enemies.

0:22.6

But on that cold November night,

0:32.3

someone was waiting. But the question was, who? I'm Kristen C.V. And this is the case of Peggy Mortimer on murder she told.

0:53.9

This episode discusses suicide, so please listen with care.

1:03.0

The clatter of a trolley bell cut through the chill,

1:07.8

echoing down Cook Avenue as dusk settled over St. Louis, Missouri.

1:14.8

Lieutenant Ira Cooper stood at the stove, ladling oxtail stew into a chipped porcelain bowl,

1:19.4

the scent of pepper and bone broth filling the corners of his small flat.

1:23.0

Outside, the sidewalks were slick with rain,

1:28.7

and downtown shop windows blinked with the first hints of the holiday season. It was late November, just days after Thanksgiving, 1937, and the city had turned gray in expectant.

1:36.7

He'd just settled in when a knock broke the silence, three sharp wraps.

1:42.8

At the door stood a young man in a soaked coat, his shoes dripping onto the welcome mat.

1:48.6

He offered up a yellow envelope, telegram for Lieutenant Cooper.

1:53.3

Cooper tipped him a dime and shut the door with a certain heaviness of spirit.

1:57.7

He already knew what the envelope would ask of him. It was from Colonel Martin Castile,

2:02.9

Missouri Highway Patrol. Please come immediately. Women murdered in Mexico. Case is stalled. Need help.

2:11.8

The word that struck him was Mexico. Not the country, but the town. 11 115 miles northwest of St. Louis, the place where

2:21.7

Cooper had once called home, where he'd read barefoot through dirt alleys, carrying books for his

2:27.1

mother, where he'd earned his first coin delivering papers, and been chased off porches for the

...

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