The spirits in prison were the demon angels who rebelled in Noah's day....not the spirits of dead people.
2 Peter 2:4...
"Certainly God did not refrain from punishing the angels who sinned, but threw them into Tarʹta·rus, putting them in chains of dense darkness to be reserved for judgment."
Jesus, after his resurrection in the spirit, went to pronounce that judgment message to those wicked spirits in Tartarus, which is not "hell" as many Bibles mistranslate.
WTS/JW misapply 2 Peter 2:4 in that they do not understand the built in chiasm or structure of Peter & Jude, which is rightly seen here:
Michael The Archangel [X1] Appendix 1 The Epistles Of Peter & Jude ComparedYOUTUBE: https://www.youtube.com/channel/UCplWZcKcFd1tNbHYPS-5t9wINTERNET...
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Jesus, was not preaching to the angels who sinned, by the Holy Ghost in Noah's day. He was preaching to mankind in that day, not angels. The angels which were cast out and fell, cannot receive redemption, so there is no need to preach to them.
No, Jesus, in His resurrection, went to speak to His disciples, not "wicked spirits in Tartarus". The timing of the WTS/JW is all off, as well as the events.
The phrase in 2 Peter 2:4, refers to when the angels which rebelled were cast out of Heaven (3rd), and sent into outer darkness (the 'space' between the unfallen worlds), which is what the word 'hell' generally means, a place of darkness, hidden, covered, not in the light (as Heaven is). The events of 2 Peter 2:4 took place long before the days of Noah, even before the creation of this earth.
[Rebellious Angels in Heaven before earth was created, angel-kind]
2Pe 2:4 For if God spared not the angels that sinned, but cast them down to hell, and delivered them into chains of darkness, to be reserved unto judgment;
[Days of Noah, after earth was created, mankind]
2Pe 2:5 And spared not the old world, but saved Noah the eighth person, a preacher of righteousness, bringing in the flood upon the world of the ungodly;
[Sodom and Gomorrah, long after the flood took place, mankind]
2Pe 2:6 And turning the cities of Sodom and Gomorrha into ashes condemned them with an overthrow, making them an ensample unto those that after should live ungodly;
Three differing events, in three differing times, just as Jude shows also.
[Egypt & Moses, mankind]
Jud 1:5 I will therefore put you in remembrance, though ye once knew this, how that the Lord, having saved the people out of the land of Egypt, afterward destroyed them that believed not.
[Rebellious Angels in Heaven before earth was created, Heaven]
Jud 1:6 And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgment of the great day.
[Sodom and Gomorrah, long after the flood took place, mankind]
Jud 1:7 Even as Sodom and Gomorrha, and the cities about them in like manner, giving themselves over to fornication, and going after strange flesh, are set forth for an example, suffering the vengeance of eternal fire.
[Reverse Chiasm, "filthy dreamers defile the flesh" refers to Sodom; "despise dominion" refers to Rebellious angels in Heaven; "speak evil of dignities" refers to Moses & Egypt, with Dathan, Abiram and Korah)
Jud 1:8 Likewise also these filthy dreamers defile the flesh, despise dominion, and speak evil of dignities.
For more, see previous link.