Washington, Sunday

Andrew Cunanan, it turns out, was not a master of disguise following a devious plan that culminated in the murder of Gianni Versace. He was a bum on the lam, desperate and inept, who escaped arrest for two months in Miami Beach because of the incompetence of the local police.

Philip Johnson, on the other hand, was a genius. He was the $7 an hour guard at a Florida firm that collected and delivered money.

On March 29, he disappeared with $20m in cash, the largest single robbery in history, and has never been seen since.

He was subject to depression, in a dead-end job handling enormous sums of cash, and devised the perfect heist. At least so far, and the FBI admits that it has no leads, and does not even know whether he has left the country.

He planned everything in advance, perhaps over several years.

He spoke Spanish and learnt Portuguese, so perhaps he is safe in South America. He established a series of fake identities and even the couple of mistakes he made did not lead to his capture.

He was the courier, the man who went into the stores and loaded the money into the armoured van while the driver remained locked in the cab.

On his last evening, he and his partner made their last round and delivered their last cargo to a nondescript building in Jacksonville, north Florida. That was where Loomis Fargo stored very large sums of money overnight ready to be delivered to the banks when they opened in the morning.

Left alone in the building with two other employees, Johnson pulled out his company gun and took charge. He treated his two prisoners well, and they, sensibly, did whatever he told them.

He loaded a van with the $20m, locked up behind him and drove into the night. He left one prisoner in his own house, handcuffed to a water pipe in a cupboard, with a jug of water and some food.

Then he drove to North Carolina, where he dropped off his second prisoner. He handcuffed him to a tree in a wood, and promised to report his whereabouts the next day.

That was his first mistake. The tree was so small that the prisoner escaped within a couple of hours and called the police.

The next mistake Johnson made was to leave the empty van near the park where he left his prisoner. It was found immediately - but Johnson's luck, or planning, saved him.

He has never been found.

Cunanan died a desperate fugitive hiding in a houseboat two miles from the scene of his last murder. Johnson has another problem: how to convert $20m in $100 and $20 bills to usable money. Even in South America, it is not usual to buy a house with cash.