A rash of decapitations and other gruesome killings have hit Tijuana since Mexican President Felipe Calderon visited the border city last week and called it a success in his drug war.
The most recent killing occurred just before midnight Tuesday when motorists found a decapitated body underneath a bridge on a road leading to the beachside neighborhood of Playas de Tijuana, according to a police report Wednesday.
Reporters at the scene saw a rope hanging from the bridge, suggesting the man had been hung from his feet but was too heavy and plunged into oncoming traffic.
The discovery came a day after two other beheaded bodies were found hanging from their feet in Tijuana.
Police said they were still conducting forensic tests on the body found Tuesday and had no immediate comment on the identity of the man or the circumstances of his death.
Earlier Tuesday, police found a human head inside a bag in another Tijuana neighborhood, but it did not belong to the body found underneath the bridge.
According to police reports, at least 16 people have been killed in the city since Sunday _ a surge from the normal rate of about two homicides a day.
Some resident feared the cartels were trying to send a message just as the city is trying to promote itself to the outside world. Calderon last week inaugurated "Innovative Tijuana," a two-week festival featuring discussions on aerospace, auotomotives and other industries that drive the city's economy. Former Vice President Al Gore is scheduled to give a speech about the environment as part of the festival Thursday.
"Obviously, they don't want it to seem like we are a society of good people. That's why they are doing these things again," said Victoria Perez Bernal, a retired dentist who along with 2,000 others attended the inauguration of the festival last week. "But what they don't know is that people are tired of this and we are starting to get organized."
Violence peaked in Tijuana in 2008 amid a showdown between two crime bosses _ Fernando "The Engineer" Sanchez Arellano and Teodoro "El Teo" Garcia Simental, a renegade lieutenant who rose through the ranks by dissolving bodies in vats of lye.
Garcia was arrested last January. While killings have continued, the most gruesome displays of cartel violence _ decapitations, hangings and daylight shootouts _ had subsided. That sort of violence has continued to plague other cities in Mexico's northern states of Chihuahua, Nuevo Leon and Tamaulipas.
"These hangings from bridges, heads, shootouts ... it hadn't happened for a long time," said Hector Elizaga, 40, who works at a Tijuana company that imports cars. "It seems like they are telling the president: 'What control? We are still in charge here.'"
At a news conference Tuesday, Baja California state Deputy Attorney General Fermin Gomez attributed the killings this week to internal disputes among the remnants of Garcia's gang.
In an interview with the AP last week, Calderon agreed that crime continues in Tijuana and said it was likely murders will fluctuate as long as cartels continue to war over drug markets and routes to the United States.
But he said other crimes, such as kidnapping and extortion, are down, and he stood by his claim that Tijuana is a success story in his war against organized crime.
"Crime has dropped dramatically since its peak in 2008," Calderon said. "Tijuana went from being a city seized by terror and focused only on questions of crime to a city motivated by hope and focused on pursuing a competitive edge in the region."
In Chihuahua state Wednesday, six prison guards were killed while driving to work in Chihuahua city, the state's capital, authorities reported.
In the northern state of Sinaloa, two police officers were killed when gunmen ambushed their patrol in Mazatlan. It was the second ambush of police in Sinaloa this week _ eight officers were killed Monday when gunmen opened fire on their patrol cars.
Associated Press writers Olivia Torres in Ciudad Juarez and Alexandra Olson and Kathy Corcoran in Mexico City contributed to this report.