Day was a graduate student at ISU in Bloomington when he disappeared at the end of August. His body was identified weeks later, having been pulled from the Illinois River near Peru.
The FBI said it's hoping to get more information from Day's close contacts to better understand the circumstances surrounding his death. The agency is engaging in a coordinated, nationwide, multi-platform social media campaign to identify new leads, including offering a $10,000 reward.
Day's mother told ABC7 she is thankful, but wonders why the FBI waited so long to get involved.
"What if they had done their job then to now, what could they have found?" Carmen Bolden Day said. "We all know time waits for nobody. The first 48 hours are the most critical you can find out stuff."
Bolden Day added that she is also offering a $25,000 reward for information. Sources at the FBI tell the I-Team they've been involved in Day's case ever since a body has been located.
The Peru Police Department also said in a written statement: "The Peru Police Department and the Jelani Day Joint Task Force, continue to coordinate efforts, follow previously identified leads and seek new information regarding the circumstance surrounding Jelani Day's tragic death. We are dedicated to following the evidence to determine what really happened that day and urge the public to reach out if they have new information regarding this case. There is no further information at this time."
An attorney for the family of Jelani Day had called for the FBI to investigate Day's death as a hate crime.
Attorney Ben Crump joined Day's family and the Rev. Jesse Jackson for a press conference in Chicago earlier this month, demanding answers in the student's death investigation.
READ MORE | Jelani Day's mother shows why she believes foul play was involved in son's death
Crump said he came to Chicago with a singular mission, which is to make it clear to the public that Day did not die by suicide, and that it's time for the U.S. attorney general and FBI to take over the case exclusively. The case is especially personal for him.
"Jelani was our fraternity brother, a member of Omega Psi Phi," Crump said. "So beyond the fact that he was one of the most promising, one of the most gifted, one of the most intelligent Black men that we have to offer the world, he was also my frat brother. So that's why we declare to make him a priority. He will be the face of Black and missing in America.
Last month, Day's cell phone was found and was sent to the FBI for further testing.
From the beginning, Day's mother has questioned the investigation by local police and the LaSalle County sheriff.
"I wasn't getting any help, I didn't have the resources, I didn't have the ability to have people out there searching for my child," she said. "I didn't have all the drones, I didn't have all the police officers. I didn't have any of that. I still don't have that."
The LaSalle County coroner ruled Day's death a drowning, but Crump rejects that notion and wants the FBI to investigate the case as a hate crime.
"It doesn't add up at all. His car was found three-and-a-half miles from the river where he allegedly committed suicide in, but then his clothes were found in another place, his wallet was found in another place, his cell phone was found in another place by other people," Crump said. "The fact that they took the license tag off the back of his car, none of that adds up to suicide. It sounds like homicide."
Anyone with information is asked to call 1-800-CALL-FBI. Tipsters can remain anonymous.
The video in the player above is from an earlier report.