Iowa police have captured a 17-year-old, accused of killing his grandparents over the weekend, after leading cops on a foot chase along railroad tracks.

Authorities on Monday had issued an arrest warrant for the teen, Isaiah Sweet, charging him with two counts of first-degree murder in the deaths of Richard Sweet, 55, and Janet Sweet, 62, whose bodies were found Sunday afternoon in Manchester, the Cedar Rapids Gazette reports.

After receiving a tip that Sweet was in Cedar Rapids, an hour away from Manchester, police spent nearly two hours searching before finding and catching the suspect.

Police told the Cedar Rapids Gazette that Sweet called a friend on Friday evening and said he drugged his grandparents, who were likely dead. A neighbor saw Richard Sweet alive at his home that night, a criminal complaint reads.

A second witness says Sweet contacted her on Sunday looking for a place to stay, saying he killed his grandparents and urged her "not to be scared." A third witness says Sweet said he was "on the run" Saturday.

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Iowa City police had Sweet in custody for five hours early Sunday morning on an unrelated matter -- before his grandparents' bodies were discovered. He was allegedly caught trying to break into a convenience store to use a bathroom, the Cedar Rapids Gazette reports.

At that time, he was charged with driving with a suspended license and released.

But after learning about the grandparents' deaths, Iowa City police reached out to state investigators for help.

Sweet was a student at the West Delaware High School in Manchester but dropped out on Feb. 3, the Cedar Rapids Gazette reports. As part of safety precautions, the doors of the school were locked Monday while two sheriff's deputies posted guard. All activities at the school on Sunday evening were also canceled.

Autopsies have been conducted on the Sweets' bodies, but the cause of death has yet to be released and police have not publicly identified a motive in the killings.

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