Major Hennadii Chastiakov, an assistant of Ukraine's Commander-in-Chief Valerii Zaluzhnyi, was killed by an explosive device in his home, Zaluzhnyi announced on Nov. 6.
The officer was killed on his birthday by explosives present in one of the gifts, Ukraine's top general wrote on his Telegram channel.
The reasons and circumstances of the officer's death are to be established in a pre-trial investigation, he added.
The media reported earlier that the 39-year-old Zaluzhnyi's assistant was killed in an explosion at his home in Chaiky, Kyiv Oblast. The officer's 13-year-old son was seriously injured in the explosion and is in medical care, according to authorities.
Chastiakov's wife reportedly said that her husband was killed by a grenade contained in a gift bag with alcohol he brought home, Ukrainska Pravda reported, citing its sources in law enforcement.
"From the beginning of the full-scale invasion, Hennadii was a reliable shoulder for me, completely devoting his life to the Armed Forces of Ukraine and the fight against Russian aggression," Zaluzhnyi said in his condolences.
The officer is survived by his wife and four children.