Jeremiah 40:14

40:14 They said to him, “Are you at all aware that King Baalis of Ammon has sent Ishmael son of Nethaniah to kill you?” But Gedaliah son of Ahikam would not believe them.

Jeremiah 41:6-7

41:6 Ishmael son of Nethaniah went out from Mizpah to meet them. He was pretending to cry as he walked along. When he met them, he said to them, “Come with me to meet Gedaliah son of Ahikam.” 41:7 But as soon as they were inside the city, Ishmael son of Nethaniah and the men who were with him slaughtered them and threw their bodies in a cistern.

Jeremiah 41:18

41:18 They were afraid of what the Babylonians might do because Ishmael son of Nethaniah had killed Gedaliah son of Ahikam, whom the king of Babylon had appointed to govern the country.