Shallum son of Jabesh conspired against him, assassinated him in public view, and took over as king.
The rest of the life and times of Zechariah is written plainly in The Chronicles of the Kings of Israel.
That completed the word of God that was given to Jehu, namely, "For four generations your sons will sit on the throne of Israel." Zechariah was the fourth.
Shallum son of Jabesh became king in the thirty-ninth year of Azariah king of Judah. He was king in Samaria for only a month.
Menahem son of Gadi came up from Tirzah to Samaria. He attacked Shallum son of Jabesh and killed him. He then became king.
The rest of the life and times of Shallum and the account of the conspiracy are written in The Chronicles of the Kings of Israel.
Using Tirzah as his base, Menahem opened his reign by smashing Tiphsah, devastating both the town and its suburbs because they didn't welcome him with open arms. He savagely ripped open all the pregnant women.
In the thirty-ninth year of Azariah king of Judah, Menahem son of Gadi became king over Israel. He ruled from Samaria for ten years.
As far as God was concerned he lived an evil life. Sin for sin, he repeated the sins of Jeroboam son of Nebat, who led Israel into a life of sin.
Then Tiglath-Pileser III king of Assyria showed up and attacked the country. But Menahem made a deal with him: He bought his support by handing over about thirty-seven tons of silver.
He raised the money by making every landowner in Israel pay fifty shekels to the king of Assyria. That satisfied the king of Assyria, and he left the country.