DALLAS » Baylor University did not report a single instance of sexual assault in a four-year span, according to federal statistics, a finding that stands in sharp contrast to the many other private and public schools that made multiple reports over the same period.

The Baptist school of 16,000 students in Waco has faced mounting criticism over its response to sex assaults on campus, and some critics contend administrators have failed to fully investigate complaints, including two involving football players who were later convicted.

“There’s always a red flag that goes up when a school reports zero incidents,” said Neena Chaudhry, senior counsel for the National Women’s Law Center. “I don’t think it’s a good sign when you’re not getting any reports because it’s probably not true.”

Among nearly 200 public and private institutions in the U.S. with similar enrollment, Baylor was one of about two dozen schools that reported no offenses.

Baylor has declined to address specific allegations, though President and Chancellor Ken Starr has decried the “scourge of sexual violence.”

Colleges and universities are required to report crime statistics to the Education Department. Prosecutors, alumni and students said they were dismayed by statistics that showed Baylor reported no sexual assaults from 2008 to 2011.

An Associated Press review of the data shows that during those years, Texas Christian University, with an enrollment of more than 10,000 students, reported 13 sex assaults on campus. Southern Methodist University in Dallas, with an enrollment topping 11,000, reported 15.

Nationally, Wilmington University’s campus in New Castle, Delaware, was the only other private institution with an enrollment similar to Baylor’s that reported no sex offenses during that time. Most reported at least a dozen assaults, with Marquette University reporting 15, Notre Dame 26, Vanderbilt recording 38 cases, and Stanford 53.

Dozens of other universities are facing federal investigations for the way they handle student sex assault allegations. For instance, a lawsuit was filed last week by a group of women alleging that the University of Tennessee violated federal Title IX anti-gender discrimination regulations and created a “hostile sexual environment” through a policy of indifference toward assaults by student-athletes.

It’s “ridiculous” to think that no assaults occurred at Baylor during those years, said McLennan County Assistant District Attorney Hilary LaBorde. At a seminar at the school last year, she said, she learned that fewer than 10 percent of women who contact the campus’ Title IX office go on to file a police report.

After that four-year span, Baylor reported an increasing number of assaults: four in 2012, 11 in 2013 and 10 in 2014. Both TCU and SMU also reported increases over the same time — with TCU reporting 32 cases and SMU 17.

The rise coincides with implementation of the federal Violence Against Women Act, which affords more protections for sex assault victims, and a 2011 warning by the Education Department that schools have a legal responsibility to investigate allegations of sexual assault immediately, even if a criminal probe is not finished.

LaBorde prosecuted two Baylor football players who were convicted of sexual assault: Tevin Elliott for a 2012 offense and Sam Ukwuachu for a 2013 assault.

ESPN’s “Outside The Lines” profiled three unnamed students earlier this month who said the school failed to act after they reported being sexually assaulted by Elliott. One of the victims said an administrator told her there were six complaints against Elliott, and Baylor could not act because “it turns into a he said-she said,” according to the report.

It’s not clear when each of the assaults is alleged to have happened.

In the case of Ukwuachu, LaBorde told The Associated Press, Baylor “did not validate” the sex assault claim made by another student.

On “Outside The Lines,” Michele Davis, a nurse who examines victims of sexual assault for the Advocacy Center for Crime Victims and Children in Waco, said she sees about eight Baylor students a year. Of those, athletes are accused 25 to 50 percent of the time, said Davis, who did not respond to calls from the AP.

Baylor’s governing board announced new measures last week to improve the school’s response to sexual assaults, including hiring more counselors and additional training for faculty and staff, but the board did not provide details. The Texas attorney general’s office, meanwhile, recently determined that the university can keep private campus police records that detail the assaults committed by Ukwuachu and Elliott.

Starr, a former prosecutor and judge best known for his work on the Whitewater investigation involving President Bill Clinton, has declined to speak publicly about the assault claims. A Philadelphia law firm hired by Baylor is reviewing the school’s response to sex assault claims, but Starr has not guaranteed that the report, which he said would “serve as a beacon for self-awareness,” will be released publicly.

Multiple phone messages left for a Baylor spokeswoman and the school’s Title IX coordinator, Patty Crawford, were not returned.

Stefanie Mundhenk, a 2015 Baylor graduate who says she was raped last year by a fellow student, criticized the school’s inconsistent response. The AP normally does not name victims of sexual assault, but Mundhenk agreed to be identified.

Mundhenk said some staff offered support and guidance, but there were obstacles, such as the campus counseling service that ultimately decided it could not help. The university’s investigation determined the other student “was not responsible,” she said, and campus police told her the matter would not be forwarded for prosecution because of lack of sufficient evidence.

“I wasn’t there for pity. I was there for justice,” she said, “and justice wasn’t done.”