Marchanti, 48, a Baltimore County teacher, was on his first one-year tour in Afghanistan and was scheduled to return in September, said his sister-in-law Trish Sauter, who was reached at Marchanti's home in Baltimore.
"He will be missed very much," said Sauter as she held back tears. The family, which was informed of Marchanti's death on Saturday, declined to reveal the circumstances of his death. The U.S. Department of Defense had made no official statement about his death as of Sunday night.
The department announced several deaths of U.S. military members in recent days in connection with escalating violence over the burnings of Qurans at a U.S. air base near Kabul.
On Thursday, an Afghan soldier turned his gun on foreign troops, killing two American soldiers, during a riot outside a U.S. base in Nangarhar province, officials have said. Rising anti-American sentiments in that country over the Quran burnings have resulted in two more American deaths since. Two U.S. military advisers — a lieutenant colonel and a major — were found dead in their office with shots to the back of their heads.
Marchanti taught physical education at several schools in Baltimore County, most recently at Carney Elementary School, Sauter said.
Marchanti joined the U.S. Army after high school and completed a three-year stint before joining the Maryland National Guard about 20 years ago, Sauter said.
"He was a very caring person. He wanted to help," she said, adding that Marchanti was a family man.
Marchanti is survived by his wife, Peggy, and four children, Aaron, Leah, Ian and Jonah, and a three-year-old grandson.
The Associated Press contributed to this article.