Yes it can. According to Wikipedia, 'When a faulty capacitor is charged, the water-based electrolyte becomes unstable and breaks down, producing hydrogen gas. Since these types of capacitors are sealed in an aluminium casing, the pressure builds up within the capacitor until either the flat metal top of the capacitor begins to bend, or the rubber sealing plug is pushed down. Eventually the pressure exceeds the strength of the metal casing and venting occurs, either by blowing out the rubber bottom of the capacitor, or bursting the scored metal vent on the top of the capacitor. When an electrolytic capacitor bursts, effects can range from a pop and a hissing noise to a small explosion. Venting is typically messy, and the acidic electrolyte must be cleaned off the motherboard to prevent further damage.'.
But explosions are rare, as the capacitors of made of aluminum that will give way much before the gas inside reaches that explosive pressure. There is a rubber vent and a aluminum vent that will give way much before that.
I doubt that an exploding capacitor can kill a person, unless the poor guy had a shock and may be an instantaneous heart attack. One possibility is the exploding capacitor triggered a secondary explosion that charred the computer and killed the engineer.
Cheers
