(CNN)A man arrested on suspicion of spying for the United Arab Emirates has allegedly died by suicide while imprisoned in Turkey, the country's state prosecutor and its state-run news agency Anadolu said Monday.
Alleged UAE spy kills himself in Istanbul prison, Turkish state media says
But the man's brother claims that he was killed, and says that his image is being "defamed."
Turkey's chief prosecutor identified the dead man as Zaki Hassan, who had been detained on charges of "obtaining confidential state information for political and military espionage." He and another man were arrested on April 4 and 5, according to Hassan's family members.
Turkish officials had been investigating whether the pair, suspected of spying for the UAE, were connected to the October 2018 murder of Jamal Khashoggi at Saudi Arabia's Istanbul consulate, according to Anadolu.
The prosecutor said that a prison guard found Hassan at 10:22am in his one-man cell in Istanbul's Silivri prison, during food distribution on Sunday.
The Prosecutor's office says they have opened an investigation.
The UAE did not respond to CNN's request for comment.
According to his family, Hassan was a Palestinian father of nine and a retired major intelligence general. He worked for the Palestinian Authority in Gaza prior to the Hamas takeover there in 2007.
Hassan had been given political asylum in Bulgaria and received a Turkish residency permit on his Palestinian passport in March, his brother, said.
The brother, Zakaria Hassan, told CNN: "Zaki was killed and did not commit suicide.
"My brother is a martyr and enough is enough to defame his image. Not only did they kill him but now they are defaming the image of my brother," he said.
"He was a father, had a Phd in political science, and was a retired intelligence general. Why would he kill himself?" Hassan told CNN on Monday.
The second suspect in the arrests was identified as Samer Shaaban, according to two Gaza families.
His wife Sameeh Shaaban told CNN that he left Gaza in early 2008 and was later named as a suspect by Hamas for an alleged plot to assassinate Palestinian Prime Minister Ismail Haniyeh -- something which she and the family denies.
"I want my husband to be released as soon as possible, as there is no evidence for his conviction. Turkish authorities and the media should be held to account for these false accusations," Shaaban said.