[2][1] She was the daughter of Amelia M. Fendler-Abrams and Alexander Abrams, both prominent physicians in New York City the 1890s.
[1] Her parents separated in 1907 and had a scandalous divorce case in March 1912, with eighteen-year-old Lillian testifying on her mother's behalf.
[14] She collaborated with her third husband, Norbert Lederer, to write the mysteries Murder in Time in 1933 and Death Comes on Friday in 1937.
[1][7] The Chicago Tribune noted that the latter was "a smartly turned mystery with an intreging cast of characters, swift action, and a dénouement that is startling but completely logical and fair to the reader.
'[15] Day's short story, "Living up to Lizzie", was adapted into the film Personal Maid's Secret, released by Warner Bros. Pictures in 1935.
[20] The Philadelphia Inquirer wrote, "Until this gossipy, but informing biography by Miss Day appeared his profile to posterity was a caricature."
[26] He was a chemical engineer, former attache to Scotland Yard, and author on crime, tropical fish and chess.