A Golden Valley man allegedly head-butted another man so forcefully this past summer that the victim fell backward and sustained a brain injury that later killed him, according to charges.

Erik Kravchuk, 28, was charged Friday in Hennepin County District Court with one count of first-degree manslaughter in the death of Aleksandre Sambelashvili.

Authorities allege that Kravchuk, seemingly unprovoked, struck Sambelashvili, 42, at a July 28 "ethnic event" at a bar in downtown Minneapolis.

Sambelashvili is a native of the Republic of Georgia.

The charges did not specify a possible motive or connection between the two men.

Sambelashvili died on Aug. 23; authorities, citing a communication mix-up, did not disclose his death until Thursday after Kravchuk was booked into the county jail.

According to the complaint: Police were called to Hennepin County Medical Center on July 29 to investigate an assault. Sambelashvili's friend told police that Sambelashvili was found the previous night unconscious on the floor of a bar.

Police recovered surveillance video that allegedly showed Kravchuk entering the bar on July 27.

Video also allegedly showed him walking toward Sambelashvili about 1:36 a.m. July 28.

"Victim does not appear aggressive and no sign of conflict is apparent," the complaint said. "As victim nears defendant, defendant suddenly and violently 'head-butts' victim."

Sambelashvili was apparently knocked unconscious immediately, the charges said. He fell backward and struck his head on the floor.

Police allegedly recovered a transaction from the bar on a credit card registered to Kravchuk's company.

When police showed him video of the head butt, Kravchuk said he did not know Sambelashvili and "refused to acknowledge that it was [Kravchuk] on video," according to the complaint.

Police informed him that Sambelashvili had died, and Kravchuk allegedly invoked his right to an attorney, ending the interview.

Sambelashvili was a research scientist at Medtronic. He was an MBA graduate from the University of Minnesota and earned a Ph.D. in biomedical engineering from Case Western Reserve University in Ohio. He authored 17 peer-reviewed papers, filed more than 25 patents and developed an algorithm that "became a key cardiac rhythm therapy feature in Medtronic's products," according to an online obituary.

Staff writer Libor Jany contributed to this report.