Veronica Guerin had studied accountancy and political research and had founded a public relations company before she joined the Sunday Business Post and Sunday Tribune. In 1994, she began to write about criminals for Irish newspaper the Sunday Independent. She used nicknames for underworld figures to avoid Irish libel laws. When she began to cover drug dealers, she received numerous death threats.

When Guerin was shot in the leg at her home on January 30, 1995, some of her critics argued that she had staged the whole thing for publicity purposes. Regardless, she vowed to continue her investigations. Independent Newspapers installed a security system to protect her. On September 13, 1995, convicted criminal John Gilligan attacked her when she tried to interview him. He later called her at home and threatened to kidnap and rape her son if she wrote anything about him. The Garda Síochána (Irish police) gave her a 24-hour escort but she did not approve of this, saying that it hampered her work.

On June 26, 1996, when Guerin was sitting in her red Opel Calibra at an intersection on the Naas Dual Carriageway, a few miles outside Dublin, one of two men sitting on a motorcycle beside her car fatally shot her five times. Guerin's murder caused outrage, and Taoiseach John Bruton called it "an attack on democracy". The following criminal investigation led to over 150 arrests and a hunt against Irish organised criminal gangs. There was also some discussion as to whether her newspaper shared any blame in her death for not preventing her more dangerous investigations.

In the wake of Guerin's death, the Irish parliament realised the potential of using tax enforcement laws as a means of deterring and punishing criminals. It then enacted the Proceeds of Crime Act 1996 and the Criminal Assets Bureau Act 1996, so that assets purchased with money obtained through crime could be seized by the government. This led to the formation of the Criminal Assets Bureau (CAB).

In November 1998, Dublin drug dealer Paul Ward was convicted of the murder and sentenced to life in prison as an accomplice because he had disposed of the pistol and the motorcycle. This conviction was later overturned on appeal, though Ward continues to serve a long prison sentence for his participation in a prison riot.

Brian Meehan was convicted of murdering Guerin and sentenced to life imprisonment.

John Gilligan was extradited from England on February 3, 2000. He was tried and acquitted for her murder but convicted of importing cannabis and sentenced to 28 years in prison; this was reduced to 20 years on appeal.