Catahoula Parish deputies caught him in woods about a mile from the scene about 1 a.m. Tuesday after a resident saw him enter nearby woods.
Ponthieux, formerly of Mansura, was armed but captured without gun play.
He is accused of shooting to death John Ellard Jr., 45, and his wife, Edris A. Ellard, 51, both of Monterey, and Annie Bell Adams, 74, of Larto. Adams and Edris Ellard are believed to be mother and daughter.
Motive for the shooting has not been revealed. Officials said Ponthieux did make a statement when captured, though they declined to divulge its contents.