GRAND RAPIDS, Mich. (WOOD) — After conducting an autopsy, the Kent County medical examiner determined Grand Rapids Drive player Zeke Upshaw was the victim of a “sudden cardiac death.”

Upshaw, 26, collapsed Saturday night at the DeltaPlex while playing during a game for the local NBA G-League team. He was rushed to the hospital, where he died late Monday morning after efforts to save his life failed.

Kent County Medical Examiner Dr. Stephen Cohle said he conducted an autopsy on Upshaw’s body Tuesday and determined that his death was the result of cardiac failure.

“We did an autopsy today. It’s my opinion that it’s a cardiac death.” Cohle told 24 Hour News 8 Tuesday. “I think he died a sudden cardiac death.”

Cohle said Upshaw also had a “slightly enlarged” heart, but he said that is not entirely unusual in athletic individuals. He added he’s not sure the slight enlargement had anything to do with why he died.

“There were some cardiac abnormalities that I hope to clarify by looking at the tissue slides,” Cohle said. “I’m going to try to characterize the exact type of heart disease microscopically.”

Cohle said he spoke with Upshaw’s mother Tuesday. He said she gave him no indication that Upshaw had a personal or family history of heart conditions. He said the family will be going through Upshaw’s belongings and medical records to see if there was a known condition that the athlete hadn’t shared with others.

“Further studies — mainly, including the microscopic examination of the heart tissue — will be forthcoming,” Cohle said. “There’s some heart diseases that you can look at them the day of the autopsy, you can look at the heart and say, ‘This guy died of a blocked coronary artery‘ or ‘This guy died of a ruptured aorta.’ This is not one of those.”

Cohle said it could take a few weeks to finish the autopsy investigation.

Upshaw’s funeral is set to take place Saturday in the Chicago area. Drive team members will travel to Illinois together to honor their fallen teammate.