The Ingersoll sisters grew up in a four-story home in Peoria known as the Cockle Mansion, with a large extended family. Ingersoll held progressive views about the intellectual capabilities of women, and his daughters studied literature, art, music (Maud was a contralato), and languages. They were taught by private tutors, as Ingersoll was a believer in secular education and wished to avoid Christian teachings in the schools of the day. In 1878, the Ingersoll family moved to Washington, DC, to a house in Lafayette Square near the White House. The family hosted large weekly gatherings which included politicians, businessmen, artists, and other leading figures discussed the issues of the day, further broadening the sisters' education.[1][2][3]
She headed the Robert Ingersoll Monument Association in an unsuccessful effort to place a monument to her late father designed by Gutzon Borglum in Washington, DC.[5]
Wallace Probasco engaged in a long extramarital affair with Mazie Ingersoll (no relation), wife of the wealthy watchmaker Robert H. Ingersoll. On December 19, 1926, in her apartment at 55 Park Avenue in New York City, both Wallace Probasco and Mazie Ingersoll were shot, and the latter killed. According to Wallace Probasco, he had broken off their affair, intending to return to his wife, and she shot him twice and committed suicide. A homicide case against Wallace Probasco was dismissed the following year. The Probascos reconciled.[1][8][9][10][11]
^ ab"MRS. PROBASCO DIES; INGERSOLL DAUGHTER: FOLLOWED FATHER'S POSITION AS AN AGNOSTIC -- ALSO WORKED FOR SUFFRAGE AND PEACE." New York Times, Feb 13 1936, p. 19.
^"MISS INGERSOLL MARRIES.: COLONEL'S DAUGHTER WEDS W. MCL. PROBASCO BY ETHICAL RITUAL." New York Times (1857-1922), Dec 31 1912, p. 5.
^"PROBASCO IS FREED, HIS STORY UNSHAKEN: LETTER MRS. INGERSOLL WROTE WHILE DYING SAYS PISTOL WAS FIRED IN STRUGGLE. AUTOPSY INDICATED SUICIDE MR. INGERSOLL "DISAPPOINTED" -- MRS. PROBASCO, AIDING HUSBAND, TELLS OF THEIR RECONCILIATION." New York Times, Mar 26 1927, p. 19
^"PROBASCO GETS BAIL IN INGERSOLL DEATH: FREED AT HEARING IN HOSPITAL AFTER OFFICIAL FINDS WOMAN KILLED HERSELF. HER LAWYER DISAGREES SAYS SHE PLANNED TO SUE THE WOUNDED MAN FOR GEMS -- DENIES SHE BORROWED FROM HIM. PROBASCO GETS BAIL IN INGERSOLL DEATH." New York Times (1923-), Dec 21 1926, p. 1