Killed the sleeping Pandava sons; brahma-bandhu
'suptan avadhinnishi balakan' (SB 1.7.35); as a brahma-bandhu he was not killed — the punishment was shaving, confiscation and banishment.
King
Ashvatthama
अश्वत्थामा
Also known as गौतमीसुतः · द्रौणिः
Ashvatthama is the son of Dronacharya, a brahmana-kshatriya; at the end of the Mahabharata war he murdered the sleeping Pandava sons and launched the brahmastra. In SB 1.7 Arjuna, on Krishna's direction, administered the punishment of shaving, confiscation and banishment (not execution). Tradition holds him immortal.
Śrīmad Bhāgavata Mahāpurāṇa 1.7.14 — Sanskrit Wikisource (pinned oldid=110178)
Son
Drona
Sage
Ashvatthama is the son of Drona. Source evidence (SB 1.7.14): Ashvatthama is Drona's son: 'drauni' (SB 1.7.14). Evidence: EXPLICIT (patronymic).
Son Kripi HumanAshvatthama is the son of Kripi. Source evidence (SB 1.7.47): Ashvatthama is the son of Kripi: 'ma rodid asya janani gautami' (SB 1.7.47) — 'his mother'. Direction: son -> mother. Evidence: EXPLICIT.
Released the brahmastra but did not know its withdrawal
'ajanann upasamharam prana-krcchra upasthite' (SB 1.7.20) — the decisive contrast with Arjuna (cf. SB 1.7.32).