According to biographer Fred Lawrence Guiles, her grandmother, Della Monroe Grainger, had her baptised Norma Jeane Baker by Aimee Semple McPherson. She obtained an order from the City Court of the State of New York and legally changed her name to Marilyn Monroe on February 23, 1956.
Here is what appears to be a birth certificate of Marilyn Monroe, born Norma Jeane Mortenson on June 1, 1926. The birth record was created by a local registrar on June 5, 1926, and this certified copy of that information was issued by a Health Officer & Registrar on October 24, 1955. It was photographed and then used for the 1981 article about the death of her father, Edward Mortenson, as depicted on the certificate. Mother was Gladys Monroe; Monroe was a surname that Marilyn Monroe officially used.
According to the original caption: Monroe‘s film studio, 20th Century Fox, stated that her father passed away when she was a baby but this certificate reveals that Edward Mortenson, who had claimed to be her father, was alive until 1981.
Source: eBay item 180815059351
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