The interview came as Ankara and Washington continue to remain at odds over the issue, with Turkey earlier submitting a formal request for Gulen's extradition.
Turkish authorities blame Gulen for the attempted coup which took place in the country on July 15 and was suppressed the next day.
Ankara believes that Gulen and his supporters were seeking to overthrow the current Turkish government, which is dominated by President Recep Tayyip Erdogan. Gulen, who has been living in the US state of Pennsylvania since 1999, has repeatedly denied the allegations and condemned the attempted coup.
Aslandogan, for his part, referred to a very clear-cut extradition treaty between the United States and Turkey which he said envisages the relevant conditions that must be met.
"A crime which would warrant extradition should be regarded as such in both countries, and there should be direct evidence of a person's involvement in this crime. Also, there should be no political undertones in the matter," he said.
"It is clear that if Gulen is extradited, he cannot expect a fair trial. Sending him to Turkey right now is tantamount to sentencing him to death," Aslandogan said.
Touching upon the Gulen movement, he said that it should be seen as an organization focusing on integration-related ideas.
"The Gulen movement is closely connected with the present-day world. In Gulen's study I saw that Islam speaks of democracy, rationalization and gender equality. It integrates modern-day symbols with Islamic traditions. The Gulen movement simply tells people that the spirit of Islam does not contradict modernization," he added.
Addressing President Recep Tayyip Erdogan's crackdown on Gulen's supporters in Turkey, Aslandogan described the situation in the country as a "humanitarian catastrophe" and as a "witch hunt".
Aslandogan was asked about the future of President Erdogan and his political regime. He replied that "it is difficult to say how much real support there is for Erdogan, given that 99 percent of the mass media are under his control, which is also the case with the results of public opinion polls."
"As for the opposition, it remains very weak and poses no threat to Erdogan," Aslandogan said, expressing serious concerns about "the future of Turkey."
Earlier, former Assistant US Attorney Nick Akerman told Sputnik that Washington cannot violate the country's Constitution by detaining and extraditing Gulen without probable cause simply to appease Turkey.
The US Department of Justice, Akerman added, must provide clear documentation that shows there is good reason to believe Gulen is guilty of a crime before shipping him overseas at Ankara’s behest.
"It would be pretty unusual to detain somebody while it [Justice Department] examines and investigates [him/her], unless there is an indictment that has been issued and there is probable cause that the person committed an extraditable crime," Akerman explained.
On Tuesday, the US State Departmen confirmed that Turkey had formally submitted a request for Gulen's extradition that was based on grounds unrelated to the July 15 military coup attempt.
Turkish officials admitted earlier this week that Ankara had yet to provide the United States with evidence linking Gulen to the July 15 military coup. President Erdogan in turn said on Wednesday that the refusal to extradite Gulen would not help US-Turkish relations.
