Sky Crime’s documentary looks back at a shocking 1970s crime spree. Plus: Dawn French and Mark Heap wrap up their secretive sitcom. Here’s what to watch tonight Sky Crime’s documentary looks back at a shocking 1970s crime spree. Plus: Dawn French and Mark Heap wrap up their secretive sitcom. Here’s what to watch tonight 9pm, Sky Crime When 23-year-old Doug Gretzler was imprisoned in 1973 for murdering 17 people across 20 days – including two children – in the US, with his accomplice Willie