The setting is of 2010. No weird science nor aliens.
There's this crime lord who climbed too quickly up the power ladder. He has an uncanny ability to know exactly what everyone within his range (20 kilometer radius) is doing. Anyone who comes into his range is recognized, not by name but he can tell everyone apart without seeing them.
The means by which he obtained this ability is unknown (or irrelevant). He is, otherwise a normal human (with common sense). His seeing & hearing ranges are normal. A very skilled assassin is sent to kill him (as skilled as you could imagine within current technology level, no magic).
The requirement is only to kill him, by any means, but avoid killing anyone else. The maximum casualties allowed is 10 deaths.
Edit 1
His power range is a sphere.
His power only lets him know who does what, instinctively. He can't tell the intention.
He won't ever get sensory overload.
Edit 2
For some who are wondering why I won't just quarantine the area then send an army after him: he would see it from 20 kilometers away (maybe more if he has spies or scouts) he would have plenty of time to put on a disguise and slip away in the mass confusion (you're attacking a city after all) and if there's no mass confusion he would just explode some buildings (setup before-hand, it's sensible to have backup plan) to cause confusion and slip away.
Why I don't just send assassin to sneak into his building and kill him in his sleep: he's well aware of his vulnerability during unconscious hours and the ability to sneak into any building is overrated in movies. It's a den, of course there will be plenty of elite guards who, once they shoot, only miss half of the times (and there's plenty of them to make up for that). Beside, who said there wasn't something like an automatic turret with facial recognition that shoots anything unfamiliar? Remember, he's sensible. He doesn't have to be a genius, he can hire geniuses any day to design his den.
Why I don't rig some beggars and detonate when they got close to him: seriously, beggars have no chance to get close to him and why would he go to places where something like that could happen? When he goes out, he uses his armored vehicles, multiple ones just to confuse people. Again, he's sensible.
Why I don't send him an explosive gift: why would he read mails and open gifts by his own hands? He has assistants for that. Explosive phone? He's sensible, why would he want a stupid expensive iPhone for? He would order one, custom made, with highest security, encryption money could buy.
Drones: it's his obvious flaws, so it's only sensible to have his building or panic room protected from such. His anti-air should be as good as any warlord. And you don't see many warlords killed by remote controlled drones.
I must emphasize again that he's sensible. Meaning he won't work alone. He's not a genius but he has money to hire geniuses. He or his consultants would recognize his obvious flaws and should have some countermeasures.
The crime lord has been subject to previous assassination attempts and is very cautious.