ALEXANDRIA, Va. — A former C.I.A. officer was sentenced to 19 years in prison on Friday for conspiring to deliver classified information to China in a case that touched on the mysterious unraveling of the agency’s informant network in China but did little to solve it.

The former officer, Jerry Chun Shing Lee, 55, pleaded guilty in May to conspiring with Chinese intelligence agents starting in 2010, after he left the agency. Prosecutors detailed a long financial paper trail that they said showed that Mr. Lee received more than $840,000 for his work.

Mr. Lee, an Army veteran, worked for the C.I.A. from 1994 to 2007, including in China. After he resigned, he formed a tobacco company in Hong Kong with an associate who had ties to the Chinese intelligence community. Mr. Lee then began meeting with agents from China’s Ministry of State Security, who assigned him tasks he admitted to taking on and offered to “take care of him for life.”

While working in Hong Kong in 2010, Mr. Lee reapplied for employment with the C.I.A. but misled American officials repeatedly in interviews about his dealings with Chinese intelligence officers and the source of his income.