Kenneth R Rosen on how British gangs are using a loophole in the law to get hold of antique firearms and untraceable bullets. Plus: Guardian editor-in-chief Katharine Viner on the 200th anniversary of the Peterloo massacre

A drive-by shooting of four girls outside a nightclub in Birmingham in 2003 shocked the country. Letisha Shakespeare, aged 17, and Charlene Ellis, aged 18, both died, innocent victims caught in the crossfire of gang shootings. It set off a huge murder investigation, and when police examined the scene they found that one of the guns used was an antique and the ammunition was untraceable.

Journalist Kenneth R Rosen tells India Rakusen how those bullets found at the scene in 2003 were the beginning of a mystery. Hundreds of ‘ghost bullets’ started to appear in crime scenes across the country and a long search began for their creator.