Isaiah Sweet, 17, was arrested in Cedar Rapids for the deaths of Richard Sweet, 55, and his wife Janet, 62, of Manchester, Iowa, The Des Moines Register reported.
Court records indicate the couple was last seen alive Friday evening.
A friend of Isaiah Sweet's told police Sweet called her Friday night and said he drugged his grandparents and thought they were dead because he couldn't find a pulse.
Darrian Marie Fleischacker said Sweet called her back the next morning and said he had killed his grandparents.
Special agent Larry Hedlund of the Iowa Division of Criminal Investigation said Isaiah told a number of people he had killed his grandparents before police arrested him.
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