https://en.wikipedia.org/wiki/Elijah
Books of Chronicles[edit]
Elijah is mentioned once more in 2 Chronicles 21:12, which will be his final mention in the Hebrew Bible. A letter is sent under the prophet’s name to Jehoram of Judah. It tells him that he has led the people of Judah astray in the same way that Israel was led astray. The prophet ends the letter with a prediction of a painful death.
This letter is a puzzle to readers for several reasons. First, it concerns a king of the southern kingdom, while Elijah concerned himself with the kingdom of Israel. Second, the message begins with “Thus says YHVH, God of your father David…” rather than the more usual “…in the name of YHVH the God of Israel.” Also, this letter seems to come after Elijah’s ascension into the whirlwind.[49]
Michael Wilcock, formerly of Trinity College, Bristol, suggests a number of possible reasons for this letter, among them that it may be an example of a better known prophet’s name being substituted for that of a lesser known prophet.[50] John Van Seters, however, rejects the letter as having any connection with the Elijah tradition.[51] However, Wilcock argues that Elijah’s letter “does address a very ‘northern’ situation in the southern kingdom”, and thus is authentic.[52]
from https://en.wikipedia.org/wiki/Elijah#Return
The question of whether Elijah was in heaven or elsewhere on earth depends partly on the view of the letter Jehoram received from Elijah in 2 Chronicles 21:12 after Elijah had ascended. Some have suggested that the letter was written before Elijah ascended, but only delivered later.[176] The rabbinical Seder Olam explains that the letter was delivered seven years after his ascension.[177] This is also a possible explanation for some variation in manuscripts of Josephus‘ Antiquities of the Jews when dealing with this issue.[178] Others have argued that Elijah was only “caught away” such as Philip in Acts 8[d] John Lightfoot reasoned that it must have been a different Elijah.[185]
