The deceased has been identified as Veeru, they said.
The teenager, resident of Panchkula in Haryana, took this extreme step yesterday, police said here.
He was arrested in a theft case and was sent to juvenile home on July 24, they further said.
Child Development and Project officer Chhinderpal Kaur said that a magisterial probe had been ordered by the District Magistrate M S Jaggi in this regard.