1 Samuel 4:12 That same day a Benjamite ran from the battle line and went to Shiloh with his clothes torn and dust on his head. 13When he arrived, there was Eli sitting on his chair by the side of the road, watching, because his heart feared for the ark of God. When the man entered the town and told what had happened, the whole town sent up a cry.
14 Eli heard the outcry and asked, “What is the meaning of this uproar?”
The man hurried over to Eli, 15who was ninety-eight years old and whose eyes had failed so that he could not see. 16He told Eli, “I have just come from the battle line; I fled from it this very day.”
Eli asked, “What happened, my son?”
17The man who brought the news replied, “Israel fled before the Philistines, and the army has suffered heavy losses. Also your two sons, Hophni and Phinehas, are dead, and the ark of God has been captured.”
18When he mentioned the ark of God, Eli fell backward off his chair by the side of the gate. His neck was broken and he died, for he was an old man, and he was heavy. He had led b Israel forty years.
Eli wasn't killed by someone.
Literal Standard Version 1 Samuel 4:21
and she calls the youth Ichabod, saying, “Glory has removed from Israel,” because of the taking of the Ark of God, and because of her father-in-law and her husband.
The original Hebrew does not contain the word "killed" or even "dead".
Noun - masculine singular construct | third person feminine singular
Strong's Hebrew 2524: Husband's father
and her husband
Conjunctive waw | Noun - masculine singular construct | third person feminine singular
Strong's Hebrew 376: A man as an individual, a male person
Was Eli killed?
No. The OP's version over-translated the Hebrew original in this verse. As pointed out by GratefulDisciple's comment, the Berean Study Bible is the only one out of 43 English translations to translate the verse that way.