Source mapping: Identifying the key actors in a story and any documents recording their actions is the next stage of the investigative reporting process. Many public records show what governments, hospital staff, corporations, the mafia and politicians have been up to. Various contacts can also help to verify or refute your original hypothesis. Always make sure you have at least two independent sources confirming the same information. These sources will serve as background experts, so make sure to add their contact details into your address book.

There are two categories of sources: primary or secondary.

Primary sources: These are sources who provide first-hand evidence or relate direct experience. For example, a patient who bought drugs from a nurse via the backdoor of a hospital could attest to the pharmaceutical black market, though he is unlikely to give you an in-depth look at what nurses do behind the scenes. A foreman at the water plant, who was instructed to make purity checks monthly instead of weekly, is also a primary source. So is the bank statement of a Cabinet minister that clearly shows payment from an international arms company. Primary sources – as long as you have verified them and made sure they are authentic – are the most valuable sources because they provide direct proof. They are also often the hardest to find. People with relevant experience may be reluctant to go on the record because they fear being victimised, and documents, like bank statements or hospital records, may be kept confidential or even restricted by privacy laws.

Secondary sources: Secondary sources include all kinds of published materials, including organisational reports and second-hand accounts (‘I had a friend who…’). Secondary sources are valuable, particularly for establishing context and background, helping to explain issues and providing leads to good contacts. However, any evidence you draw from them – as well as the person they originated from – should be checked and verified.

You can also differentiate four types of source material: human, paper, digital and crowd-sourced.

(a) Human sources: Many sources fall into this category: direct role players, eyewitnesses, experts and interested parties, both eager and reluctant. Be sure you know the status, credentials and motivations of the people you approach. If you are working on the water privatisation story, the representatives of anti-privatisation organisations would be able to provide a great deal of information from the opposing side. But that information will come from a particular position, and representatives of organisations are often speaking on behalf of much larger groups of people. When they summarise group views, they may organise and edit community opinions in ways that change or exclude important aspects – sometimes unintentionally. Therefore, you need to seek a variety of viewpoints. If you are speaking to people from a community, be sure your selection of voices is demographically representative: Women, men, young, old, from various income and interest groups. Human voices give your story authenticity and make it come alive.

(b) Paper sources: These can include books, newspapers, official records, directories, and business documents, such as contracts and bank statements. This may include ‘grey material’, which are widely circulated but may not have been published (e.g. studies commissioned from private organisations, academic dissertations) or which may be officially confidential. But there are some challenges to the paper trail: Sometimes we just do not know if the evidence exists, the public records are in disarray, or worse, there are no freedom of information laws that allow the media to pull out the relevant document. Officials in such parts of the world may stall the process of getting such data out, because they fear the repercussions of the information being public. As such, it is critical to establish early on what documents you need for your story, where and how they are stored, and how you can access them. If advance permissions are necessary, make sure to do this as early as possible since official permits can take weeks and months to come through.

(c) Digital sources: These include information on websites and digitally stored records. The amount of information online is dazzling but, as with any other source, you need to verify where the information came from. You need to check what officials are writing about themselves, and how friends and family describe them. But remember that the web is relatively uncontrolled: Anyone with access can post anything, including complete fabrications. In addition, web information often stays online for a long time; sometimes long after it has become outdated. Always check the most recent sources first. For further help, download a free copy of the Verification Handbook published by the European Journalism Centre (EJC). It provides tools and techniques on how to deal with digital content.

(d) Crowd-sourcing: This new tool combines human and digital sources. It involves media outlets drawing readers to investigative stories by inviting them to contribute, such as sharing their experiences on Twitter or asking questions on a Facebook live video.

Type of sourceUseful forStrengthsPossible problems
HumanGiving life and authenticity to a storyInterviewing someone face-to-face usually does not require high-tech resources

First-hand experience make a story more convincing
People have biases, prejudices and may lie

May only provide anecdotal evidence — need to ensure interviewees are representative

People may be victimised for talking to the press — how will you protect them?
PaperProviding hard evidence

Providing history and context
Secondary sources broaden background research beyond what you can tackle yourself

Primary documentary sources (e.g. bank records) are 'on-the-record' and reliable
May be protected by privacy laws, censorship etc.

Hard or slow to access

May need specialist knowledge to understand e.g. financial documents

Can produce a 'dead' or over-academic story with no live voices
DigitalCan do all of the above, depending on what is retrievedCan be done from your computer, including accessing sound and video

Information is posted quickly and from a huge range of national and international sources
May end up with a dead story

Security threats of the Internet

Verifying 'facts' on the Internet can be arduous

There may be laws in place to help you get access to data. National laws differ, not just in their titles but also in their scope, which makes one-size-fits-all advice difficult to give. You should research the laws in your country before you start your investigation.