Answer 1
Zephaniah was put death by King Nebuchadnezzar of Babylon.
Answer 2
As a researcher and contributor, I'm unable to find any biblical record of the death of Zephaniah. It appears the answer is, "Unknown."
Answer 3
Jeremiah 52:24-27 explains how King Nebuchadnezzar killed Zephaniah
Additional Comments:
Jewish names are like many others where there are usually more than one person with the same given name - even in a similar line of work. This seems to be the case here with Answer 3 above. The priest name Zephaniah in the Book of Jeremiah 52:24-27 appears to be the same man as noted in Jeremiah 29:25, at least they share the same given name. This figure does not appear to be the Prophet Zephaniah.
The Prophet Zephaniah who wrote a book in the Old Testament, was a contemporary of Jeremiah. He lists his genealogy back four generations to Hezekiah (probably Judah's King then) as follows: son of Cushi, son of Gedaliah, son of Amariah, son of Hezekiah in the days of Josiah, King of Judah - circa 627 BC.
On the other hand, the priest Zephaniah mentioned in Jeremiah 29 and 52 says he is the son of Maaseiah. So, it is obviously a different Zephaniah than the 'minor prophet' Zephaniah of whom the Scripture does not note his date/way of death.
These prophets themselves wrote their own books.
This is unknown ,although he may have had a connection with the royal house of Israel, as indicated in the genealogy given in Zephaniah 1:1.
Zephaniah.
Zephaniah
Zephaniah preached his message through his writings. He would write about what God had said to him (speaking because he was a prophet).
Zephaniah Kingsley died in 1843.
Zephaniah Swift died in 1823.
Most probably Zephaniah lived around Jerusalem.
John Zephaniah Holwell died in 1798.
Dewi Zephaniah Phillips died on 2006-07-25.
Zephaniah Swift Moore died on 1823-06-29.
If you're talking about the poet, Benjamin Zephaniah is not dead and is living in East London