Turkey’s Haberturk news website first carried the report on Monday, with senior journalist Cetiner Cetin, who broke the story, saying the suspect hanged himself in Silivri prison on Sunday.
The suspect’s death was later confirmed by the state-run Anadolu Agency.
Al Jazeera’s Sinem Koseoglu, reporting from Istanbul, said Turkish authorities would investigate how he managed to kill himself as he was being held in solitary confinement.
“The Justice Ministry said they believe he used his clothes, his pyjamas, to hang himself,” she said.
She added that according to Turkish authorities, “the two men were detained in mid-April, they are Palestinian nationals and admitted to working on behalf of UAE intelligence.
“Authorities believe that since relations between Turkey and Saudi Arabia, the UAE and Egypt have been strained since the military coup in Egypt in 2013, those countries were trying to build up a new system of intelligence gathering because of the situation.
“They were believed to be spying on Muslim Brotherhood members living in Turkey since the coup,” she added.
According to a previous report by the Reuters news agency, citing a senior Turkish official, one of the two men arrived in Turkey in October 2018, days after Saudi journalist Jamal Khashoggi was killed inside the kingdom’s consulate in Istanbul.
The other person had arrived later to help his colleague with the workload, the unnamed official told Haberturk.
It is not clear if their arrival in Turkey was linked to the Khashoggi case.
Khashoggi, a prominent critic of Saudi Crown Prince Mohammed bin Salman, was killed by Saudi operatives, provoking an international outcry.
The CIA and some Western countries believe Prince Mohammed, Saudi Arabia’s de facto ruler, ordered the killing, an allegation Saudi officials deny.