How Newsnight investigates

This is where the real slog happens. It is time consuming and can be tortuous and ultimately fruitless.

The coup agreement appears to have been signed by Simon Mann

We go all out to get documents: inside documents.

In our investigation into the attempted coup in Equatorial Guinea we obtained the contract between the plotters.

It spelled out that the leader of the plot would receive £10 million if he succeeded and his team would get millions more.

Arsenal

For the investigation into Arsenal's strange activities it took two years to persuade an investigating magistrate to show us his files.

Broadcast 1 June 2006.

Liz Mackean followed the trail which proved Arsenal secretly funded a Belgian football club which got African players work permits.

Freedom of information

We also put in freedom of information requests. The problem is that it can take months of appeals before you get the information you want.

For our film on "How Britain helped Israel get the Bomb" we ultimately obtained top secret documents from British intelligence on nuclear exports, which revealed the whole story for the first time.

Broadcast 9 March 2006.

Michael Crick talked to nuclear weapons experts about Britain's exports of plutonium, uranium 235 and heavy water to Israel.

Documents give you more names to chase. They in turn give you more leads to follow.

You don't have to be a journalist to use FOI. Here's the BBC's guide to help you.

Freedom of Information Guide

Financial analysis

Sometimes expert analysis of financial documents can reveal the full story.

That's how we discovered that two years after the tsunami disaster a billion pounds was sitting unused in Red Cross accounts while victims were still in temporary accommodation.

Broadcast 19 December 2006

Niall Sookoo analysed an official UN website that tracks the delivery of money promised for disaster relief.

"Follow the money" is always a useful guide. It led us to former Home Secretary David Blunkett's share dealings in DNA BioScience. A week later he resigned saying media pressure had made it impossible to do his job.

Broadcast 2 November 2005.

Michael Crick looks at the succession of embarrassing events which led to David Blunkett's downfall.

Sources

In some of the murkier areas - crime and intelligence for instance - confidential sources are essential.

These are contacts who we have built up over many years who for instance helped us uncover the connections between Islamist terror networks in Britain. Broadcast 30 April 2007.

In the case of the Equatorial Guinea coup contract we were able to run it past a source who could show us similar contracts for other mercenary operations.

To see how we put flesh on the bones by collecting evidence to illustrate the story, click on the Evidence tab.