I have been working in a public hospital in Tehran over the last few weeks. The authorities are covering up the number of dead protesters and their causes of death. The official statistic is 20 dead – that's wrong. In our hospital alone there were 38 riot deaths in the first week. Most died from gunshot wounds.

A colleague told me that in his hospital there were a further 36 gunshot casualties and 10 deaths. Four public hospitals admitted wounded protesters during the riots, but it is hard to know the total figures of dead. Other hospitals were prevented from helping. Basiji militiamen attacked doormen in one hospital for letting in wounded protesters. In the hospitals that were allowed to function, the basijis replaced the hospital admissions staff and took the IDs of wounded patients.

Medical staff are under huge pressure to cover up the injuries they treated; I know one doctor who killed themself.

If the patients died of gunshot wounds the basiji confiscated their bodies and told the families they had been "transferred" for organ donation. They removed the bullets and returned the bodies with a different postmortem report. By the second week the basiji were better organised and took the bodies directly from the streets. There were many dead the hospitals never saw.

As for the injuries, they speak for themselves. There were multiple points of gunshot impact – proving the authorities were shooting liberally. Their victims were indiscriminate.

Two pregnant women were shot – one through the spleen, she survived and the other died. For the latter, the authorities say a photograph of her circulating the internet had been taken in another country, but that's not correct. She was wounded, treated and died in Tehran. They shot her three times. One bullet penetrated the foetus's spine.

How can a doctor lie on his medical records after operating on a case like that?

Many of my friends and my cousin even (who was wounded) saw snipers up on the rooftops during the protests. They said these snipers were targeting people through their rifle lenses. The injuries we witnessed in hospital testify to this. One 32-year-old patient had gunshot impact entering the sub-umbilical region with an exit wound on the thigh, which proves the bullet came from above.

Many protesters also saw foreign basiji; they were yelling "Arab" as they attacked us. They were not speaking Persian. We do not know who these fighters were.

Together with the basiji on the bikes, wearing civilian clothing – these were the violent ones. Others were young conscript boys, mostly from the provinces, wielding rubber anti-riot batons and Palestinian scarves. They made jokes as though they didn't really understand what they were doing. But their leaders were different, they looked you in the eye and they knew you didn't support them. You felt like a permanent target.

From what I have seen and heard, this medical cover-up has been happening all over the country. But unofficially, medical staff report dead in Isfahan, in Shiraz, in many places. Like here, the authorities are making sure the hospitals don't reveal the numbers.

And they want the people to keep quiet, too.

Even in the south of Tehran, among families of the martyrs from the Iran/Iraq war, the old revolutionaries, people don't agree with this violence. In the hospitals they tell us they don't believe in Ahmadinejad any more but are forced to pretend otherwise because they are employed by the state.

Whoever you are in Iran and whatever you do, it is easy to doubt yourself. Many of us who witnessed this state aggression, watch Iranian news and listen to the authorities and start to question what we saw. The bias is so great you begin to feel isolated, question what you witnessed.

At night, the basiji swept the riot zones and cleared away evidence. They want us to think nothing happened. They want us to be blind.

Now it seems Michael Jackson's death has made the world forget Iran.

But the number of disappeared continues to increase here. First they were taken by the police and basiji during the protests – and now in the house raids that happen night after night. It is getting harder and harder to protest, no matter how many ways we invent to show our frustration.

Between 10pm and 10.30pm some Mousavi supporters still stand on their roofs to yell "Allahu Akbar" (God is greatest). In 1979, the revolutionaries did the same and claimed they could see Khomenei on the moon to guide them.

Now we are not so superstitious, but the darkness is overwhelming. There are fewer voices every night.

The authorities are tracking everybody. They are confiscating mobile phones for contact details, they are tracing computer IDs of people who used Twitter or Facebook. I have friends who have been arrested – people who had just come from Europe to work for a couple of weeks and got caught up in the violence. It is all such a mess. We haven't heard from most of them.

Prison is a question of luck. If you get arrested by the basiji and taken to a basiji centre – that's the worst. The basiji are not supposed to have centres of their own, they are meant to deliver to the prisons, but they have their own rooms – and that's the most dangerous place to be.

Then there's Evin prison. I have one cousin who was taken there for the last student uprising. There is a huge empty room where they ask you to identify protesters. If they sense you are afraid, they force you into confessing anything and identifying anybody. It's not so much what you say as the fact they debased you.

Most protesters are moved from prison to prison, so they become untraceable. Knowing the cover-up in the hospitals, I worry many protesters might be "untraceable" forever.