But because he has already been jailed for 19 months, Colliton, 43, was eligible for immediate release. His lawyer, Howard Greenberg, said he expected the defendant to be released Thursday.
Corrections officials did not immediately return an after-hours call Thursday night.
The 38-year-old mother of the two underage sisters pleaded guilty in April 2006 to endangering the welfare of a child. She admitted she allowed her girls to have sex with Colliton, knew he was giving them money and gifts, and said she had asked him for money for herself.
Colliton, who is married with five children, was formerly with the prestigious Manhattan law firm Cravath Swaine & Moore.
He admitted when he pleaded guilty that he had sex many times with one girl younger than 15 and another under 17 between Dec. 25, 2000, and March 1, 2005. Colliton also admitted he visited a prostitute younger than 17 between August 2000 and February 2004.
He had faced as many as 30 years in prison if he had been convicted of several counts of rape and sodomy.