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Research Doctor Accused of Hiring Hitman to Take Out Rival in Oil Deal Gone Wrong Called Himself ‘His Royal Highness’ on Bounced Checks: Feds

Dr. Serhat Gumrukcu appears in a screengrab taken from an Enochian BioSciences promotional video posted on YouTube.

Dr. Serhat Gumrukcu appears in a screengrab taken from an Enochian BioSciences promotional video posted on YouTube.

Federal prosecutors have revealed a possible motive behind what they have described as a coast-to-coast murder-for-hire scheme that ended with the death of a northeastern Vermont man in January 2018. The case, which recently resulted in the arrest of a California medical research doctor, was a matter of retaliation after an alleged oil deal went bad, according to newly filed court papers.

The victim, Gregory Davis, 49, was “arrested” from his home in front of his wife and children one winter night by a man pretending to be an apparently convincing version of a U.S. Marshal. Prosecutors believe the phony law enforcement officer was the murderer who dumped Davis’s body in a snowbank near St. Johnsbury, Vermont, a few miles from his home.

Jerry Banks, 34, of Fort Garland, Colorado, was arrested earlier this year. He isn’t charged directly with murder, but federal prosecutors have said that they believe he is, indeed, the hired gun who posed as a U.S. Marshal and killed Davis. Banks is charged with kidnapping.

After allegedly killing Davis, prosecutors have alleged that Banks called Aron Lee Ethridge, 41, of Henderson, Nevada, to “inform him [Ethridge] that Davis had been successfully kidnapped and murdered.” Ethridge was accused last month of conspiring to help kidnap Davis.

The question has always been why.

Walmart security footage (left) shows a man the FBI believes to be Jerry Banks, who is pictured at right in a Colorado driver's license photo. (Images from an FBI affidavit filed in federal court in Vermont.)

Walmart security footage (left) shows a man the FBI believes to be Jerry Banks, who is pictured (right) in a Colorado driver’s license photo. (Images from an FBI affidavit filed in federal court in Vermont.)

As Law&Crime reported last week, Dr. Serhat Gumrukcu, 39, of Los Angeles, California, and Berk Eratay, 35, of Las Vegas, Nevada, were arrested after a Vermont grand jury indicted the duo for allegedly conspiring to use interstate commerce facilities — namely, cell phones — in the murder of Davis. Both men made appearances in their respective Western districts upon their arrests.

Eratay’s attorneys asked a Nevada federal judge to release him from custody pending trial. Federal prosecutors opposed the request by pointing to the possible sentence if convicted (a mandatory life sentence or the death penalty) and the defendant’s “strong foreign ties, significant assets,” “significant risk of nonappearance,” and “danger to the community.”

“There are no release conditions that would sufficiently mitigate those risks, and Eratay should be detained pending transfer to the charging district for trial,” the feds wrote to the judge.

The document continues:

The indictment alleges that Eratay conspired with Serhat Gumrukcu and others between May 2017 and February 2018 to cause interstate travel and to use and cause another to use interstate facilities in aid of a plot to pay someone to kill Gregory Davis. In separate, related indictments, the grand jury charged Jerry Banks with kidnapping Davis and charged Aron Ethridge with conspiring to kidnap Davis. The charging documents outline a conspiracy among these four men to have Banks travel to Vermont to murder Davis for money. The conspiracy accomplished the goal when Davis was murdered in January of 2018.

It then pointed to the possible motive by adding yet another batch of names to the tangled web—and alleging that the doctor referred to himself as “HRH” or “His Royal Highness” on bounced checks:

In the early investigation of the case, Serhat Gumrukcu was identified as a likely suspect involved in the murder because Gumrukcu and his brother, Murat Gumrukcu, were the only people who appeared to have a dispute with Davis that would potentially be a motive for Davis’s execution. In 2017, Davis was threatening the Gumrukcus about going to the FBI with evidence that the Gumrukcus were defrauding him in a multimillion-dollar oil deal that the Gumrukcus had entered into with Davis in early 2015. The Gumrukcus failed to perform on the deal and had made various claims about their attempts to perform. Davis believed that the Gumrukcus had lied to him about various matters. During 2017, Serhat Gumrukcu was facing felony fraud charges in California state court. One aspect of those fraud charges involved bounced checks Serhat Gumrukcu had provided to the middleman in the oil deal, Gregory Gac. On the bounced checks, Serhat Gumrukcu falsely called himself “HRH Serhat Gumrukcu,” a reference to “His Royal Highness.”

The accusations continued by referencing the biosciences company which Gumrukcu helped to launch — a company which immediately distanced itself from him when it learned he was arrested:

That same year, 2017, Serhat Gumrukcu was putting together a successful deal that came together soon after the murder, namely, his significant ownership stake in a biotech company, Enochian Bioscience. Gumrukcu therefore had a strong motive to prevent Davis from reporting yet another fraud, and likely threatening the Enochian deal. At present, Serhat Gumrukcu appears to own over $100 million worth of Enochian stock. In May 2022, about a week before his arrest, Serhat Gumrukcu generated $2 million in cash from an Enochian stock sale.

Neither Serhat nor Murat Gumrukcu had traveled to Vermont to personally kill Davis, so the most likely plot involved a hired killer. Murat Gumrukcu, who lives in Turkey, visited the United States between December 2017 and March 2018. He was staying at Eratay’s former apartment in Las Vegas at the time of the murder. Federal agents executed a search warrant at Eratay’s apartment before Murat left the United States. Both Gumrukcus were interviewed in early 2018 about the murder, denying any involvement. Indeed, Murat Gumrukcu falsely denied contact with Gregory Gac, the middleman in the oil deal. Serhat Gumrukcu falsely minimized his involvement in the oil deal. Murat Gumrukcu has not returned to the United States since March 2018.

The document then asserted that Banks “had no relationship with either Serhat Gumrukcu or Gregory Davis.” The alleged connection took time to unravel:

The government discovered a chain connecting them: Banks was friends with Aron Ethridge, who was friends with Eratay, who worked for Gumrukcu. Multiple pieces of evidence supported the link. Banks met with Ethridge on various occasions in late 2017 as the murder scheme was being finalized. Ethridge was the first person Banks telephoned after the murder. Ethridge did not appear to have direct contact with Gumrukcu, but he did have contact with Eratay. Indeed, the first call Ethridge made after receiving the postmurder call from Banks was to Eratay’s phone. Ethridge also had no connection with Davis. Eratay was the obvious link between Ethridge and Gumrukcu.

The money also required investigation. Again, from the document:

The government also developed substantial corroboration of Eratay’s role in the conspiracy. Eratay’s bank records reveal over $150,000 in wire transfers from Turkish accounts controlled by Gumrukcu between June and October of 2017, as the murder scheme was building. Eratay carefully and secretly transformed those funds into cash at the same time. Further, Eratay’s email account showed that he documented personal information about Davis in July 2017, including his full name, date of birth, place of birth, and cell phone with a Vermont area code.

The government asserted that though the investigation appeared to have gone cold from the public’s perspective, it remained ongoing — but “covert” — as agents tracked down the necessary leads.

“The coconspirators, from Banks to Gumrukcu, likely thought that they had gotten away with the murder,” federal prosecutors wrote.  But that unraveled when the government “chose to take overt steps.”

The feds said one of the witnesses — Ethridge — immediately flipped:

On April 6, 2022, Banks was arrested in Wyoming. During a custodial interview, Banks made a number of false exculpatory statements. The next day, Ethridge was approached by law enforcement. As noted in the affidavits that will be submitted prior to the detention hearing, although he denied knowledge of any scheme in his initial consensual interview, Ethridge soon reached out to law enforcement to come clean about his role. Ethridge admitted that he hired Banks to kill Davis and that he was in turn hired by Eratay (his former neighbor and friend for years) and Gumrukcu to find someone to murder Davis. Ethridge’s admissions are highly credible, as they are consistent with the other evidence in the case, and because Ethridge has no motivation to falsely implicate himself in a murder. Ethridge has since been indicted and remains detained. The government anticipates that he will be a witness at trial against Eratay, Gumrukcu, and Banks.

At the same time, federal agents interviewed Eratay at his home, as Eratay acknowledges. He spoke willingly to federal agents, but in doing so, made a number of false exculpatory statements, including a denial of knowing anything about Davis.

Magistrate Judge Cam Ferenbach, sitting in Nevada, denied Eratay’s request to be released pending trial.

Some of the relevant documents, including an FBI affidavit, are below:

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Aaron Keller holds a juris doctor degree from the University of New Hampshire School of Law and a broadcast journalism degree from Syracuse University. He is a former anchor and executive producer for the Law&Crime Network and is now deputy editor-in-chief for the Law&Crime website. DISCLAIMER:  This website is for general informational purposes only. You should not rely on it for legal advice. Reading this site or interacting with the author via this site does not create an attorney-client relationship. This website is not a substitute for the advice of an attorney. Speak to a competent lawyer in your jurisdiction for legal advice and representation relevant to your situation.