THE BLOODSTAIN'S SECRET: IS CARTEL ENFORCER DEAD?

MAZATLAN, Mexico, Feb. 27 -- The remains of Frankie O's disco are a scar on
this once-beautiful beachfront, a dung-colored pile of concrete collapsing
like a child's sand castle washed by the tide.

This ruined pleasure dome was once the palace of Francisco Arellano Felix,
the eldest of the six brazen brothers who run Mexico's most powerful drug
cartel. While Frankie and his siblings danced and drank, they also bribed
every policeman and politician in sight, buying protection, building a
multibillion-dollar family business on deals signed in blood.

Frankie went to prison. Now Mexico wants his blood. The authorities want to
check his DNA against the bloodstain left by a man whom the Sinaloa state
police shot and killed a mile down the road from the disco on Feb. 10,
Carnival Sunday.

They have good reason to believe that the man, who carried a gold- plated
handgun and a fake federal police ID, was Frankie's brother, Ramon Arellano
Felix, 37, the cartel's famously violent enforcer.

The face on the fake ID looks quite a lot like Ramon's 10-year-old picture
on the F.B.I.'s 10-most-wanted fugitives list, minus a shaggy haircut and a
drinker's double chin. That face has all but convinced Donald J. Thornhill
Jr., a United States Drug Enforcement Administration agent who fought the
gang for years while in Mexico and is now based in San Diego.

"I wouldn't bet my next paycheck on it, but I'm 99 percent sure it's him,"
Mr. Thornhill said with pleasure on Wednesday.

The bloodstain may be a fitting legacy for a man said to have murdered
scores of people for both business and pleasure. At any rate, it is the
main clue the authorities have to go on now. Mexico finds itself in the
awkward position of chasing a drug lord's ghost.

Mr. Arellano Felix lived fast, and he may have died young. But so far he
hasn't left a corpse.

The word on the street, according to United States law enforcement
officials, is that Mr. Arellano Felix was indeed in Mazatlan two Sundays
ago, as masked revelers were preparing for the Carnival parade. They say
that he was gunning for a drug rival, Ismael Zambada, but that Mr. Zambada
had bought-and-paid-for friends in the state police who protected him.

The official Mexican version of the case is that the state police spotted
two armed men driving a Volkswagen the wrong way down a one- way street,
pursued them and killed them after a wild chase on foot through the Plaza
Gaviotas Hotel.

All agree that the next day two mysterious impostors claimed the bodies,
paid $600 cash for a cremation and took away the ashes in two urns, one
black, one white. No one in officialdom said a word about the case for nine
days.

Masked police officers staged a reconstruction of the shooting on the
street Tuesday afternoon, with plainclothesmen posing as the men they
killed. A passer-by gazed at the scene.

"How weird," he said, and kept on walking.

Other circumstantial clues are piling up. Two assault rifles found after
the shootout, an AK-47 and an AR-15, were used in the slaying of two
federal judges in Mazatlan three months ago, said Mexico's attorney
general, Rafael Macedo de la Concha.

The Arellano Felix gang was blamed for that crime, and the rifles suggest
that "this was not some ordinary gunslinger," said the governor of Sinaloa,
Juan Millan.

But given the history of corruption and connivance in Mexican
drug-enforcement circles, more than a shred of public skepticism prevails
about the official version of the case. The daily paper Noroeste asked 100
people in Mazatlan if they thought Ramon Arellano Felix was really dead.

A resounding 19 percent said yes.

Twenty years ago, the Arellano Felix family began building an empire here
in Mazatlan, founded on brick after brick of the strong marijuana from the
mountains above Mexico's Pacific coast. Francisco built five houses, two
flanking the disco and three on Shark Avenue, each more grandiose than the
next, all now abandoned.

Then, in the mid-1980's, the group's founding father -- Ramon's uncle,
Miguel Angel Felix Gallardo, a corrupt Sinaloa state police officer who
served on the governor's protective detail -- had a flash of criminal genius.

He sought and won payment in cocaine, not just cash, from the Colombian
cartels. The gang was no longer a group of glorified mules, but multi-ton
distributors of the drug. Official D.E.A. estimates say it now handles as
much as 40 percent of the cocaine consumed by Americans, worth hundreds of
millions of dollars a year wholesale.

The Arellano Felix gang set up shop in Tijuana and won its reputation as
the most ruthless criminal syndicate in Mexico, taking control of the
frontier bordering southern California by the time-honored techniques of
murder, terror and torture.

For Ramon, the security and enforcement chief, security meant bribing
police officers, prosecutors and judges. Enforcement meant killing
uncompliant ones.

While Mr. Thornhill, the D.E.A. agent, veered among the past, present and
conditional tenses in discussing the nasty life of Mexico's most-wanted
felon, he was happy to propose an epitaph on his presumed death.

"The man is a sociopath," he said. "He was a stone-cold killer. The world
would be a better place without him."