Police in Anne Arundel County say they obtained an arrest warrant on Friday for 47-year-old Cynthia Mills, who later surrendered.
Mills was implicated in the plot when Wendell Mansel was arrested in August in Leesburg, Va. after attempting to hire an undercover police officer to kill his wife. It was later that investigators determined Mills and Mansel were having an affair.
Police said Mills provided some of the money and helped plan the scheme. She was ordered held without bond.
Mills has been charged with conspiracy to commit first-degree murder, solicitation of murder, and attempted first-degree murder.