UNC has been embroiled in a wide-ranging scandal involving student athletes since 2010 - when more than a dozen football players had to sit out all, or part of, the season after allegations of improper benefits surfaced.
Five people have been indicted on charges alleging they gave cash and other benefits to players to encourage them to sign with certain agents when they turned pro.
Separately, there were allegations athletes got improper academic help, including plagiarism, tutors who violated rules, and athletes taking no-show classes for credit.
After an SBI investigation, Orange County District Attorney Jim Woodall announced in December the indictment of the former chairman of the African and Afro-American Studies program, Julius Nyang'oro, on a charge of obtaining property by false pretenses in December. Woodall alleges the professor took $12,000 for a class he did not teach. Nyang'oro has pleaded not guilty.
A UNC review of classes within the department found 54 department classes that had little or no indication of instruction along with at least 10 cases of unauthorized grade changes for students who did not do all the work.
The classes were popular with athletes. They made up about 45 percent of enrollments. Nyang'oro stepped down from his chairmanship shortly after UNC began investigating the classes in 2011. He retired in 2012.
In a joint news release Friday, University of North Carolina President Tom Ross and UNC-Chapel Hill Chancellor Carol L. Folt said they intend to address any questions left unanswered during previous reviews with the new probe.
"We - the UNC Board of Governors, UNC-Chapel Hill Board of Trustees, Chancellor Folt and I - have said all along that we would re-evaluate next steps once the SBI had completed its investigation," Ross said.
They've retained Kenneth L. Wainstein, a 19-year veteran of the U.S. Justice Department, to do the probe.
In addition to the criminal probes of the scandal, in 2012, UNC commissioned former Gov. Jim Martin to investigate the academic irregularities.
Martin said his investigation found no link between the school's athletic department and the alleged academic fraud. He said there was no evidence coaches knew what was going on.
In the wake of the scandals, former UNC Chancellor Holden Thorp stepped down. UNC also fired former head football coach Butch Davis and former athletics director Dick Baddour resigned. Both men have said they were not aware of - or were involved - in any of the irregularities.
After conducting its own investigation, the NCAA said the school was "responsible for multiple violations, including academic fraud, impermissible agent benefits, ineligible participation, and a failure to monitor its football program."
Penalties imposed by the association included a one-year postseason ban, reduction of 15 football scholarships, vacation of records, and three years probation.
UNC also recently made national headlines when CNN reported that too many of its student athletes read poorly.
UNC challenged the accuracy of the report and said it was conducting its own investigation.