Mexico arrests suspected cartel leader in U.S. jet skier case By Tim Gaynor MEXICO CITY (Reuters) - Mexican officials said on Monday they had arrested a suspected drug cartel leader believed responsible for the murders in 2010 of dozens of migrants and an American who was killed as he jet skied on a lake on the Texas-Mexico border. Mexican marines arrested Salvador Alfonso Martinez Escobedo, known as "Squirrel," on Saturday evening in Nuevo Laredo, Mexico, across the border from Laredo, Texas, after a car chase and a shootout earlier in the day, Mexico's presidency said in a news release. The driver was armed with a rifle and had a pistol tucked into his waistband when he was ordered by troops to surrender after the chase, authorities said. He subsequently identified himself as Martinez, who authorities said is the suspected head of the Zetas cartel in Tamaulipas, Nuevo Leon and Coahuila states, all of which border Texas. Mexican authorities said Martinez was the mastermind of the murders of 72 migrants from Central and South America in San Fernando, Tamaulipas, in August 2010, in the one of the worst single acts of cartel violence in Mexico. In addition, he is a suspect in the murder of a Tamaulipas police commander who was found beheaded as he was investigating the high-profile death of jet skier David Hartley. Hartley and his wife, Tiffany Hartley, of the Denver area, were riding jet skis across Falcon Lake to photograph the ruins of a church, Tiffany Hartley told U.S. authorities. She reported that they were approached by men in two or three boats who opened fire as the couple attempted to speed away and that her husband was shot twice before going under the water. His body has never been recovered. The U.S- Mexico border bisects Falcon Lake, and the Hartleys were on the Mexican side of the lake when they were shot. The murder drew widespread attention in the United States, especially in Texas. "This came as shock after two years," Tiffany Hartley's mother, Cynthia Young, told Reuters on Monday when asked about the arrest. We're trying to piece it all together. Around 60,000 people have been killed in raging drug-related violence in Mexico over the last six years since President Felipe Calderon sent the military to crack down on the cartels. The Zetas, formed around a group of former Mexican soldiers, has emerged as the most brutal cartel fighting for turf. Additional reporting by Jim Forsyth; Editing by Corrie MacLaggan and Paul Simao