If your daughter or brother just disappeared, you would probably go to the police. But what if the police were the ones who took them?

That is the reality for thousands of families in Egypt, where the government is carrying out a brutal crackdown on dissent and freedom of expression.

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Ha'na el Taweel's daughter Esraa has been held without trial in Egypt for more than three months, and human rights groups say she is just one of thousands political prisoners being locked up for simply protesting or being associated with certain movements.

"I can't believe that Esraa is in prison," Ms Taweel told 7.30.

"When I say those words 'Esraa in prison' I still just cannot believe it."

Two years ago, 23-year-old Esraa participated in protests commemorating the anniversary of the Egyptian revolution.

While there, she was shot in the back by security forces and spent six months learning how to walk again.

Esraa now lives with a permanent disability and relies on crutches to get around. But that did not stop Egyptian authorities coming for her.

Family did not know if student was alive or dead

"Esraa left home on June 1," Ms Taweel said.

"She went out with her friends, everything was normal until we lost contact with three of them. Esraa didn't return home, all of their mobiles were off."

The arts student and keen photographer had been having dinner with two friends at a popular restaurant on the Nile.

Suddenly, they were surrounded by plain-clothes police officers. They were taken away in a white van and for 15 days her family had no idea where she was.

"During these 15 days I didn't have one positive thought," Ms Taweel said.

"We didn't have anything to assure us, we didn't know even, God forbid, if she was alive or something had happened to her."

Finally, more than two weeks after Esraa disappeared, her sister Duaa received some information.

"A girl called me and she said, 'I was visiting a relative at Al Qanater women's prison and I saw Esraa being taken into the prison'," Duaa said.

"This girl described to me the clothes that Esraa was wearing and this is what she was wearing 16 days earlier."

Duaa and her mother went straight to the prison to see if they could confirm Esraa was there.

They waited outside for hours and were told nothing until they saw her, crying, being taken out from a prison truck.

"When I saw her I started calling her name, 'Esraa!' I wanted her to look at me," Duaa said.

"She continued to cry and she pretended that she didn't see me. She was looking at the ground. She kept ignoring me.

"We learned later that they had threatened her and said they would arrest us, too. So she was scared for us and she pretended that she didn't see me."

Esraa el Taweel's family learnt where she was after a friend saw her in prison. ( Supplied )

Letters from prison describe nightmare existence

Accused of "spreading false news" and being affiliated with an illegal organisation, Esraa is still in jail but has not been charged with anything.

"[Esraa's] lawyer asked for any evidence or any screen shots to prove this, but the prosecutor hasn't provided any evidence," Duaa said.

"She is detained for accusations that just never happened."

Once a week for an hour, the family get to go visit Esraa in prison.

"She always says to me and Mum, 'please take me home, I don't want to stay here'," Duaa said.

"It's very hard when it's time to say goodbye and we have to leave."

Esraa has managed to smuggle letters out of jail describing the conditions inside.

"The prison is scary and horrible," she wrote.

"Now I cannot walk on my own, and I need someone to take me to the toilet all the time ... The strip search and body inspections we repeatedly go through are very humiliating and invasive ... The only time I feel I'm alive is when my family visits me."

Esraa wrote that before being transferred to jail, she was held at the notorious state security premises.

"I had nothing to do but pray and weep with rivers of tears ... Hearing voices and screams of torture victims, men crying out loudly," she said.

Torture of political prisoners common

Local human rights groups have estimated more than 250 Egyptian political prisoners have died in detention due to torture or medical negligence in past two years.

Tarek Hussein said he was haunted by thoughts of what his little brother had endured at the hands of Egypt's police.

"It is the worst feeling ever to know your little brother is in jail being tortured and you can't do anything to help him," he said.

Mahmoud Hussein, 19, has been held for more than 500 days without charge. ( ABC )

In 2013, his brother Mahmoud, then 18, was arrested on his way home from a demonstration. He has now been held for more than 500 days without charge.

"At every place they took Mahmoud, he was tortured," Mr Hussein said.

"He was tortured for hours on end. One morning he was taken to the prosecution office, where he saw my parents, and he begged them not to give up on him.

"He said, 'please take me home with you. I can't take it anymore, the torture. I can't stay here'.

"The current situation for freedom and human rights in Egypt is very bad. It's the worst situation Egypt has been through in decades."

'We did not have a revolution to end up in jail'

Egypt researcher for Amnesty International, Nicholas Piarchard said Esraa el Taweel and Mahmoud Hussein were just the tip of the iceberg.

"We estimate there are thousands of political prisoners in Egypt - no one knows how many," he said.

"People in jail just for their opinions, for going to a protest. President [Abdel Fattah al-Sisi] is really just cracking down on any form of dissent whatsoever.

"We are calling for the immediate release of these prisoners.

Tarik Hussein is haunted by the torture inflicted upon his brother Mahmoud in prison. ( ABC )

"We are calling on western governments to stand up to Sisi and call him out on this."

For the families involved, there is no one to turn too, nobody who can help. Speaking out is all they have - and even that is done at a huge risk.

"It's not only Esraa, many girls like Esraa, Egyptian girls, are in prison who are innocent and haven't done anything wrong," her mother said.

"So what if a girl walked in a demonstration, should she get five years?

"All the parents who have their innocent daughters in prisons - when there is days, months and years that their daughters are not at home ... it's very hard."

Mahmoud Hussein's brother still clings to the revolutionary hope of the Arab Spring of four years ago.

"For Mahmoud and the other people who have been jailed for expressing their opinions in Egypt ... despite the difficult time in prison and the length of your detention, this brutal regime that is arresting young innocent people will not last forever," he said.

"We did not have a revolution just for you to end up in jail. In the end the jails will be emptied."