Was Jesus' death legitimate?

Archaeologist Ron Wyatt claimed before his death to have discovered the Ark of the Covenant buried under several meters of rock and dirt, just outside the city of Jerusalem. He believed the Ark had somehow been buried directly under the site of the crucifixion. Part of his discovery was the presence of a dark substance that had dripped onto the mercy seat, and which appeared to be blood.

It was at this time, as Ron recalls, as the instant realization of what had happened here dawned on him, that he passed out. When he realized that the crack in the ceiling was the end of the crack he had found in the elevated cross-hole many feet above him, and the black substance was blood which had fallen through the crack and into the stone case.

Ron then knew that the Ark of the Covenant was in the stone case: But the most overwhelming realization was that Christ's Blood had actually fallen onto the Mercy Seat.

Source

It is widely rumored that the nation of Israel has the Ark of the Covenant in its possession in an undisclosed location, awaiting the rebuilding of the temple.

Christ Himself seems to be the new mercy seat, according to Romans 3:25, wherein Christ is referred to (in the original Greek) as the One "Whom God hath set forth to be an hilasterion through faith in His blood." Hilasterion refers clearly to the mercy seat of old in Hebrews 9:5.

It may also be edifying to note that upon the death of our Lord Jesus Christ, the veil into the Holy of Holies in the temple was rent.

EDIT: User @Ray has correctly pointed out that the interpretation of the word hilasterion in Romans 3:25 is debatable. Indeed, a quick search of the word yields multiple forum questions. At least one PhD dissertation is focused on this tricky word (cf. here). My apologies for not realizing the deep hermeneutical territory into which I have transgressed.

Also keep in mind that,

In 586 BC, the Babylonians destroyed Jerusalem and Solomon's Temple. There is no record of what became of the Ark. [source]

So most likely in Jesus' day the ark was not in the temple.

Revelations 11:19 Then, in heaven, the Temple of God was opened and the Ark of his covenant could be seen inside the Temple

I'm not trying to solve the mystery of the ark here but merely point out that it's entirely possible that the law could have been fulfilled with the ark in heaven after Jesus arose and ascended.

You are conflating, I think, the manner and location of the shedding of the blood with the fact of the shedding of the blood. Put simply, Jesus was the perfect spotless Lamb of God whose blood is shed for the remission of sins; there was no requirement that his blood be shed on the Jewish altar.

Consider the archetype of this sacrifice in God's command to Abraham to sacrifice his son. That was to be valid, even though there was no temple or altar.

Gen 22

2 Then God said, “Take your son, your only son, whom you love — Isaac — and go to the region of Moriah. Sacrifice him there as a burnt offering on a mountain I will show you.”

...

13 Abraham looked up and there in a thicket he saw a ram caught by its horns. He went over and took the ram and sacrificed it as a burnt offering instead of his son. 14 So Abraham called that place The LORD Will Provide. And to this day it is said, “On the mountain of the LORD it will be provided.”

15 The angel of the LORD called to Abraham from heaven a second time 16 and said, “I swear by myself, declares the LORD, that because you have done this and have not withheld your son, your only son, 17 I will surely bless you and make your descendants as numerous as the stars in the sky and as the sand on the seashore. Your descendants will take possession of the cities of their enemies, 18 and through your offspring all nations on earth will be blessed, because you have obeyed me.”

Hebrews 10:1 (KJV)
For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.

I think you can say from Hebrews 10 that the Old Testament sacrifices were a picture of Christ's sacrifice more than that his death was a fulfillment of Old Testament requirements.

Edit: Here are the verses I wanted (emphasis on verse 23):

Hebrews 9:19-24 (KJV) For when Moses had spoken every precept to all the people according to the law, he took the blood of calves and of goats, with water, and scarlet wool, and hyssop, and sprinkled both the book, and all the people, Saying, This is the blood of the testament which God hath enjoined unto you. Moreover he sprinkled with blood both the tabernacle, and all the vessels of the ministry. And almost all things are by the law purged with blood; and without shedding of blood is no remission. It was therefore necessary that the patterns of things in the heavens should be purified with these; but the heavenly things themselves with better sacrifices than these. For Christ is not entered into the holy places made with hands, which are the figures of the true; but into heaven itself, now to appear in the presence of God for us: