Police in Pakistan have released a sketch of a possible suspect in the kidnapping of an American from his home in the eastern city of Lahore.

Development expert Warren Weinstein was snatched by eight gunmen on August 13 after they overpowered security guards and broke into his house.

The black-and-white sketch released to Pakistani media on Thursday 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. In the appeal, a copy of which was sent to VOA, 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.

Meanwhile, Punjab province’s Law Minister Rana Sanaullah told VOA on Thursday that Federal Bureau of Investigation agents were aiding Pakistani authorities in their investigation, because the U.S. agency has access to technology not available to Pakistani law enforcement.

Sanaullah also said that police were focused on Weinstein’s driver and one of the security guards, who were reportedly from Pakistan’s northwest.

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.

Last month, a Swiss couple was kidnapped in Pakistan’s southwestern province of Baluchistan.