All four were indicted with union boss John Dougherty.
Michael Neill, Marita Crawford, Niko Rodriguez, and Brian Fiocca faced various charges, including embezzlement and wire fraud.
All four are residents of Philadelphia.
Dougherty maintains his innocence and is set to stand trial in January.
Dougherty resigned as union boss in November 2021, after a conviction in a separate corruption trial.
According to the U.S. Attorney's office:
Neill, 56, served as the Training Director of Local 98's Apprentice Training Fund. He pleaded guilty to four counts of embezzlement of labor union assets, one count of theft from a union employee benefit plan, and one count of making and subscribing to a false federal income tax return. He is scheduled to be sentenced on April 7, 2023.
Crawford, 53, served as Local 98's Political Director. She pleaded guilty to four counts of wire fraud, the object of which was to obtain money and property from Local 98 by means of false and fraudulent pretenses, representations, and promises. She is scheduled to be sentenced on April 4, 2023.
Rodriguez, 31, was employed by Local 98's Apprentice Training Fund and by Local 98. He pleaded guilty to six counts of embezzlement of labor union assets. He is scheduled to be sentenced on April 4, 2023.
Fiocca , 31, was employed by Local 98 as an office employee. He pleaded guilty to six counts of embezzlement of labor union assets. He is scheduled to be sentenced on April 6, 2023.