How are police drones catching drones conducting illegal activity in Japan?

A recent test by the Tokyo Metropolitan Police Department used a six-propeller drone carrying a 10-foot by 7-foot net to snag a smaller drone. The department intends to use the strategy to thwart criminals who've taken to using drones to commit an array of crimes, including an incident last April in which a drone carrying a payload of radioactive material landed on the Japanese prime minister's helipad.