The U.S. Special Representative for Afghanistan and Pakistan says the Federal Bureau of Investigation is working with Pakistani authorities in the search for a kidnapped American.

Ambassador Marc Grossman told VOA Thursday the FBI had received “excellent cooperation” from Pakistani officials, “especially the authorities in Punjab” in the hunt for development expert Warren Weinstein.

Punjab province's Law Minister Rana Sanaullah says the FBI has access to technology not available to Pakistani law enforcement.

Weinstein was snatched by eight gunmen on August 14, after they overpowered security guards and broke into Weinstein's house in the eastern city of Lahore.

Pakistani police released a sketch Thursday of a possible suspect in the kidnapping. The black-and-white rendering shows a young man with short dark hair.

Police have been interrogating Weinstein's three security guards and driver. But so far, there have been no leads and the kidnappers have not contacted authorities or made any ransom demands.

Weinstein served as the director in Pakistan of a U.S.-based development consulting company, J.E. Austin Associates. The 70-year-old worked in Pakistan for more than five years and was scheduled to end his assignment and return to the United States this week.

The president of J.E. Austin Associates, Kevin Murphy, has issued an appeal for Weinstein's release. Murphy says friends and family are devastated by Weinstein's disappearance and are particularly concerned about his health. He says Weinstein is in need of his medications.

Pakistani police say the kidnappers convinced Weinstein's guards to open a gate just before dawn last Saturday, by offering to give them food. This type of generosity is common during the month of Ramadan, when people fast during daylight hours.

Kidnappings for ransom are fairly common in Pakistan, and foreigners are occasional targets.