A forensic anthropologist "was able to determine that the skull has characteristics consistent with those of an East or Southeast Asian male," a statement from the coroner's office reads.
"Given this information, we are able to rule out that the skull is that of missing IU student Lauren Spierer," the statement continues.
The identity of the victim remains a mystery, and the coroner's office said it will rely on DNA tests to help them identify the man.
Speculation that the skull could be Spierer's was fueled in part by a blog post by Charlene Spierer, the missing girl's mother, who speculated that it could be her daughter and wrote of the "agonizing" wait for more information.
Although it would normally take about two months to identify or rule out Lauren Spierer, the coroner's office expedited tests to make things easier on the Spierer family and half a dozen other families with missing relatives, who had also been in touch with the Marion County coroner's office.
Spierer was 20 years old when she went missing in the early morning hours of June 3, 2011, after a night partying with friends. She was last seen leaving a friend's apartment in Bloomington, Ind.
Images from a surveillance camera show the 4-foot-11, 90-pound college student walking barefoot at 4:30 a.m. as she left the apartment. She never made it to her own apartment, which was just three blocks away.
Since then, police have triple-checked evidence and fielded thousands of leads, while Spierer's parents have repeatedly appealed to the public for help finding their daughter.
They've made TV appearances, called news conferences, held fundraisers, and started a website -- findlauren.com -- where they've posted regular updates. The last blog entry from Spierer's mother, Charlene Spierer, is dated Aug. 2, but more recent messages from her Twitter account reveal her frustration.
"Waiting is exhausting," Charlene Spierer wrote Friday afternoon in a message that was retweeted dozens of times by followers and well-wishers.
Spierer's parents have also offered a reward; initially set at $125,000, it was doubled to $250,000 earlier this year. The family put up its own money, and increased the reward offer with the help of an anonymous donor and Indianapolis Colts owner Jim Irsay.
Since Lauren Spierer's disappearance, her parents have been outspoken, at times criticizing their daughter's friends, accusing them of holding back information. Some of Spierer's friends have retained lawyers, and at least one has claimed he has no memory of the night she disappeared.
The White River skull was the latest high-profile lead, coming a year and one month since Spierer disappeared. Spierer's parents called attention to the June 9 skull discovery by publicly wondering if the skull could be their daughter's.
Authorities from the Marion County Coroner's Office said it's not just the Spierer family -- half a dozen families with missing relatives have also called about the skull, they said.
"In the days ahead, a family will have answers they have been desperately seeking," Spierer's mother, Charlene, wrote in a blog post.
The skull "has been submerged for some time, at least more than a year," said Deputy Coroner Alfie Ballew. If water levels hadn't dipped because of the summer drought, it's unlikely anyone would have found the skull, Ballew said at the time.