An American diplomat posted to Pakistan has been found dead in his Islamabad residence.

Keith Ryan, 37, apparently took his own life on Monday just before a scheduled return to the United States to visit his wife and 8-year-old triplets, the State Department said. Pakistani authorities are still investigating the death.

Ryan was an attache for the U.S. Immigration and Customs Enforcement agency and had previously worked for the Border Patrol and the Immigration and Naturalization Service where he was assigned to the violent gang task force.

"Mr. Ryan was a well-respected, trusted, and longtime member of the U.S. Mission in Pakistan," the U.S. Embassy in Pakistan said in a statement. "His death is a great loss. He will be sorely missed by all who have known and worked with him here in Pakistan."

His father, Bob Ryan, a sports columnist for the Boston Globe, remembered his son for his academic determination and conservative political outlook. He was a graduate of Trinity College in Connecticut and the London School of Economics.

"As anyone who has been confronted with the suicide of a family member can tell you, the only word to describe the sensation is 'devastated,"' Ryan said in an obituary on the newspaper's Web site. "We will always have questions."

In addition to his father, Keith Ryan leaves behind his wife of 12 years, Kate; his children, Conor, John, and Amelia; his mother, Elaine, and sister, Jessica.