Police say 55-year-old William Cain of Richmond is lodged at the Madison County jail on a charge of attempted murder.
Richmond Police Chief Larry Brock told the Lexington Herald-Leader that officers sent a substance found at the bottom of the coffee pot for testing, but were "satisfied" after their investigation that it was rat poison.
The Richmond Register cited family court records in reporting that Deborah Cain had filed for divorce earlier this year, but the motion was withdrawn in April.
Jail records do not indicate whether William Cain has an attorney.