Gradually, law-abiding people learned a new code of conduct: Keep your head down, don't ask too many questions, keep away from the restaurants and luxury boutiques where gangsters hang out. Family gatherings end early; everyone wants to get home soon after sunset.
About eight years ago, Castrejon kept his oldest boy from leaving Culiacan. Generations of the family had stuck together here. It was important to stay, he advised.
But this year, when his youngest turned 17 and wanted to leave, the door was open.
"I used to be afraid to have my children away from us," said Castrejon, 48. "Now the greater fear is that they stay."
Police at risk
Pedro Rodriguez, 41, has been a police officer for half his life in one of the deadliest places on the planet for cops. He got into law enforcement straight out of the army. He thought the discipline he admired in the military would continue in the Sinaloa police force. And he liked the authority that a policeman's uniform gave him.
It all changed several years ago, he said.
"It used to be, as a uniformed police officer, I could raise my hand in the road and stop an 18-wheeler," Rodriguez said. "Today the truck would run right over me."
More than 100 police officers have been killed in Sinaloa this year, most of them gunned down. Countless others have fled, or taken bribes and changed sides. As much as 70% of the local police force has come under the sway of traffickers, by some estimates.
It is widely believed here that many legislators and other politicians are elected with the help of narcotics money. The exchange: veto power over the naming of top police commanders.
Rodriguez knows he can be betrayed by a corrupt fellow officer. So, he says a prayer every day before he leaves the modest home where he lives with his wife and four children. He works in a city that can seem normal on the surface, its streets clogged with traffic, office workers going to lunch.
Then those same streets turn into a shooting gallery. Gunmen in dark-windowed SUVs open fire on rivals or cops, day or night. Five federal and state policemen were killed in a hail of bullets on Culiacan's prominent Emiliano Zapata Boulevard one recent night. The truck with their bloodied corpses came to rest outside a busy casino under blue and purple neon lights and fake palm trees. It was the third time in recent weeks that an entire squad of agents was wiped out in an ambush. No one is ever arrested; shootings, even of cops, are hardly investigated.
"Twenty years ago we knew of the handful of big mafia dons, but they were discreet," Rodriguez said. "Today we are dealing with the apprentices, who want to get rich very fast, who commit enormous excesses, who want to be noticed."
That chaos might make some nostalgic for the old days, when a few Sinaloa dynasties dominated the drug trade, as they had for generations. Amado Carrillo Fuentes branched out from Sinaloa into Chihuahua in the 1980s and '90s and ran the Juarez drug network that made him one of the richest men on the planet, owner of a fleet of jets and vast real estate holdings the world over.
As the centralized system broke down, the Sinaloans met a new challenge: the Gulf cartel.
Based in the state of Tamaulipas, the Gulf gang was reputed to have ties with, and the protection of, Raul Salinas de Gortari, the brother of former Mexican President Carlos Salinas de Gortari. After the arrest of its leader, Osiel Cardenas, the Gulf cartel became the first of the drug mafias to introduce a paramilitary army.
The narcotics ring recruited from Mexican and Guatemalan army special forces and formed the Zetas, ruthless hit men. The Zetas left one of their earliest calling cards in the town of Uruapan in Michoacan state in September 2006, when they tossed five severed heads onto the floor of a dance hall.
The Sinaloans in turn beefed up their security, and the Zetas on the other side trained additional recruits. Now several hundred, most between 17 and 35 years old, operate as mercenaries, investigators say.