Egyptian journalist Jamal Al-Jaml disappeared at Cairo airport after returning to Egypt from Turkey on 22 February.
In a Facebook post his son, Baha Al-Jaml said: "My father was tired and wanted to come back to Egypt. The moment he reached Cairo International Airport he disappeared mysteriously, and we could not reach him."
Baha said his father could not bear the thought of not seeing him again.
In a 2014 article for Al-Masry Al-Youm Al-Jaml criticised the government and General turned President Abdel Farah Al-Sisi later called him to warn him. Fearing for his safety the journalist left the country for five years.
Al-Jaml's lawyer has said that on Sunday Egypt's State Security Prosecution ordered his 15-day detention on remand for working with the opposition media in Istanbul.
The legal period in which detainees are allowed to be held in pretrial detention in Egypt is two years and even then, it is supposed to only be used in an emergency.
However, for so many of Egypt's political prisoners this pretrial detention is renewed over and over again.
In Istanbul, Jamal was presenting a TV programme on the opposition channel Al-Sharq.
A number of opposition activists and rights groups have expressed their solidarity with him and said that they fear for his life in detention.
Al-Jaml suffers from diabetes and hypertension which could be extremely dangerous in an Egyptian prison where inmates are systematically denied medical care as a form of torture.
The overcrowded and unhygienic conditions have made prison cells a hotbed for coronavirus and little preventative measures have been put in place to stem or treat the virus.
At least 100 detainees died in prison last year as a result of medical negligence.