Prosecutors say there is no suggestion that U.S. Rep. John Conyers, D-Mich., is connected to his wife's bribery plea, but questions remain, analysts say.

Detroit City Councilwoman Monica Conyers last month pleaded guilty to accepting a bribe from a prospective city contractor, and could face up to five years in prison. But even though investigators who probed the case say her 80-year-old husband is not facing any allegations, questions about what he may have known about his spouse's illegal income continue to swirl, The Washington Post reported Sunday.

The Post said attention in Detroit has focused on a 2007 letter John Conyers wrote to the Environmental Protection Agency to indicate his backing of a troubled Michigan waste-management project. Unnamed sources told the newspaper Conyers had previously opposed the plan, but later urged the EPA to reverse its rejection of a bid by businessman Dimitrios Papas to transfer permits that would have helped the project.

Papas, who had held fundraisers for Monica Conyers, had earlier hired a consultant, Sam Riddle, at her urging, but Papas denies any connection between Riddle's hiring and John Conyers' letter, the Post said.