(CNN) -- Mexican authorities have detained a Zetas drug cartel leader suspected in the 2010 Falcon Lake killing of American David Hartley, a spokesman for Mexico's Navy said Monday.
Salvador Alfonso Martinez Escobedo, accused of being a regional leader of the Zetas in three northern Mexican states, was detained last week and presented to the media Monday.
Martinez, known as "The Squirrel," is also suspected of being behind of the 2010 massacre of 72 migrants in Tamaulipas, in addition to other slayings and prison breaks in northern Mexico, Mexico's Navy said in a written statement. He is accused of leading the Zetas in the Mexican states of Tamaulipas, Nuevo Leon and Coahuila.
The Navy did not provide details about exactly why or how authorities believe Martinez is connected to Hartley's killing on the lake, which straddles the U.S.-Mexico border. The arrest appears to be the first officials have publicly tied the killing.
Authorities said Martinez is also connected to the killing of a Mexican state police investigator who had headed the investigation into Hartley's killing.
Hartley's wife, Tiffany, has told police that she and her husband were on a Sea-Doo personal watercraft on the lake on September 30, 2010, to visit a half-submerged church, when they were ambushed by assailants who shot David Hartley in the head.
She said she was unable to haul his body onto her watercraft before being forced to flee.
On Monday, Tiffany Hartley's mother said the family was "totally shocked" to learn of the arrest.
"We are going through the process of trying to confirm the information and expect to have a formal statement tomorrow," Cynthia Young said.
A Texas sheriff who helped investigate the case said Monday that Martinez wasn't on a list of five suspects' names that he has handed over to the FBI.
"Based on the information I have, he may have been the one responsible for that area, but not the one responsible for the actual killing," said Sigifredo Gonzalez, sheriff of Zapata County, Texas.
"If this is, in fact, true that he was involved, it's a welcome sign that the Mexican government is trying to solve the killing of yet another American citizen on Mexican soil," Gonzalez said.
Mexican officials also said Monday that Martinez was suspected to be responsible for "the execution of more than 50 people by his own hands in different parts of the country."