Longtime Indiana Supreme Court Justice Frank Sullivan Jr. announced Monday that he is stepping down after nearly 19 years on the court to accept a teaching post at Indiana University's law school in Indianapolis.

News of Sullivan's impending departure came hours after the court's newest member, Mark Massa, was sworn in as the 107th Supreme Court justice by the man he replaced on the five-member court, former Chief Justice Randall Shepard. Massa, who had been Daniels' chief counsel in the governor's office from 2006 to 2010, took the oath during a private ceremony Monday morning.

Sullivan, 62, said his departure had been in the works since last fall, when he began talks with the Robert H. McKinney School of Law about a teaching position. He said he signed a teaching agreement last Tuesday, but will remain on the court until near the start of the fall semester.

"I've been here almost 19 years now and I'm sort of reaching an age when I thought that if I was going to do one more big thing before I retired, I probably ought to be getting about it," said Sullivan, who was state budget director under Democratic Gov. Evan Bayh before Bayh appointed him to the five-member court in 1993.

Republican Gov. Mitch Daniels will choose Sullivan's replacement from candidates selected by the Indiana Judicial Nominating Commission. It'll be Daniels third appointment to the court, following Massa and the 2010 appointment of Steven David, a decorated Army officer who once served as chief defense counsel for Guantanamo Bay detainees. David replaced Justice Theodore Boehm, who retired.

McKinney School of Law Dean Gary R. Roberts said he expects Sullivan, who was an adjunct professor at the school from 2007-2009, to teach classes in business law and corporate finance.

"Having Frank Sullivan join our faculty is an exciting and extraordinary opportunity to bring in someone with a great mind and academic temperament to teach our students both theory and practice and to add to our scholarly culture," Roberts said in statement.

Sullivan said he hopes female lawyers and judges will apply for the vacancy, adding that he believes the state's high court should better reflect the state's population.

Indiana has had only one female justice in the state's history — Myra Selby, who served for five years before stepping down in 1999.

Under the state constitution the Indiana Supreme Court can have no fewer than five and no more than nine members. The General Assembly would have to act to add justices to the court. Sullivan said he would prefer that the court had seven members because the state "is big enough and complicated enough and diverse enough."

Sullivan graduated from Dartmouth College in 1972 and the Indiana University Maurer School of Law-Bloomington in 1982. He and his wife, Cheryl, have three adult sons. Sullivan is an avid runner who has competed in the Boston Marathon three times in the last decade.

The Indiana Judicial Nominating Commission will select a new chief justice from among the court's five members.

Acting Chief Justice Brent E. Dickson said Sullivan was the "driving force" behind the state Supreme Court's electronic case management system, called Odyssey, that shares information online at no cost.

"Justice Sullivan's many accomplishments as a jurist and a judicial leader will long be remembered with gratitude," Dickson said in a statement.