It can be nerve-racking. I remember a terrifying journey to a football match in the company of a football hooligan called Nightmare - he wasn't quite sure about me and was boasting about slashing a policeman's throat within a foot of MY throat. You don't know what will happen if your cover is blown - when I was in Moscow filming a subject in a club, my camera equipment beeped when I went through the metal detectors; there were men with guns at the doors and I had no idea what could possibly happen. Fortunately, the company I was in and my photographer's jacket meant I was left alone.
It's important to get your details right. For the football investigation I nearly made a fatal error when I had a tattoo done - I had claimed that it was a couple of years old but I'd had a relatively new Chelsea logo done. I think that puzzled our boy Jason but it didn't actually spark an alert in him - we were very lucky.
Keep a firm sense of who you have to be in each world. Don't allow any of your subjects to imprint upon you - I find that if I treat the subjects on a very shallow basis then they don't embed themselves and nothing too much is left behind. I've had death threats but I'm being well looked after in a BBC safe house.
Donal MacIntyre's next investigation, into international fraud, can be seen on `MacIntyre Undercover', next Tuesday at 9.30pm on BBC1. His book, `MacIntyre: One Man... Four Lives' is published by BBC Worldwide (pounds 6.99).Reuse content