Just google 'blockchain analysis' and a few will show up:

https://www.elliptic.co/
https://www.coinfirm.com/
https://www.scorechain.com/
https://crystalblockchain.com/
https://www.whitestream.io/

(there are or at least used to be more of such companies but some got bought out)

and maybe Kim Nilsson of wizsec: https://www.blogger.com/profile/00130450507411246919

Hmm, like I said, it will be hard to prove that input1 and output2 (change address) belongs to walletA just from that single transaction.
ChainAnalysis and other pro blockchain forensics will basically do a guesswork here unless you have used those addresses together in one transaction (inputs).

Consider hiring another pro: Professional Data recovery; to be able to restore walletA from the drive where it was deleted;
if it's a hardware device, nevermind.

then you can only prove 2 things:
1. you own address B by signing a message using its private key (wallet is a total of many keys and their corresponding addresses. you send and receive bitcoin from one or more addresses and any proof that you can provide is from individual addresses)
2. you received coins from address A


you don't need to use chain analysis company for this. any block explorer website could be used to achieve this. you must first gather all the addresses that you know of and then search them one by one in a block explorer and see where the coins are coming from or going to.

for example you know your address(es) B and you know you initially send coins from your address(es) A to it. so simply search address(es) B in a block explorer, go to its first transaction and see what address is paying it. copy the corresponding transaction ID, that is your proof that B has received X amount of coins from A.
you know your exchange address(es) EX, do the same and look for address(es) B and A in it. each received transaction is one of your deposits. copy those transaction IDs. these are proofs of your deposits and their amounts.

here is an example block explorer link: https://blockchair.com/bitcoin/

If you do not have access of wallet A, then you can't prove that wallet was belongs to you. Whatever other evidence you will provide that's all are available on blockchain. So anyone could provide that to court. Only way to prove ownership without any risk is sign a message from the address. I don't know if OP mixing up wallet with address. But if you made transaction from wallet A then change address should belongs to wallet A, it will not go automatically on wallet B if you don't put address during transaction.

Can you describe which clients you had used ? And how you had lost access of your wallet A? The only perfect way to prove yourself is recover your wallet or private keys. I don't believe some other specialist could help regarding that issue without recover private keys or wallet. Otherwise everyone will call themselves satoshi nakamoto by provide evidence of related stuff without sign message. Because all transaction history stored on the blockchain. It's not enough to prove ownership.

So actually you need prove ownership of change address? If so, then you must have access your wallet or private key of that address. I think there is not such as any mark for change address on the blockchain.

So try to recover your wallet file or something related stuff that could help recover your wallet.

On the other hand you told you sent remain fund to wallet B from change address. Then why you need prove ownership of that address, as @AdolfinWolf said at end you may sign message from wallet B from where you sent fund to second exchange. That should be right way.

First of all, which jurisdiction? US, ASIA, Europe, there are different laws in different jurisdictions.

If you need a list of good lawyers, then I would say for US you have Kyle Roche at https://rochefreedman.com/kyle-roche they helped Kleiman estate against Craigh Wright. If you are in the UK you BCandLaw link here: https://bcandlaw.com/category/news/ if you want Asia, then its very different if you go China (HK), Korea or Japan.

Analaysis its very easy. Just let me know what tx you have and you can have a chain-link for free...

/KX

There are a lot more (especially if you include invidividual persons taking such work like the guy behind wizsec), chainalysis just gets mentioned the most in the press.

I'm not sure exactly WHY, or what you need to prove, considering you have access to wallet B (where your funds are currently stored?)
Or, are we talking about the 175BTC that got stuck in an account / hacked, and that you now need to prove YOU actually sent, and not the opposing part, (the ones who supposedly accessed your account?)

...
The only reputable blockchain analysis firm i know is https://chainanalysis.com - but i don't think they offer such services for individuals, or at least, they don't anymore. You could contact them and see if they're willing to help you out somehow. (175BTC) is a large amount.

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I think these two posts are very conflicting:
Did the actions in the post below happen almost simulteanously; meaning;
you sent 175 BTC to exchange X (from WALLET A) => then the change went to wallet B => wallet B sent that to exchange X,Y.

Or- was it like this. Wallet A 175BTC => Exchange X. Exchange X 275BTC => Wallet B.
If an accurate description of the timeline is more like the first, see [1]

Proof of this is simply provided by looking at the blockchain. (as HCP stated.)


Okay; so let me get this right: (you already have your funds under your control;)? but; someone is suing you saying that these funds were from wallet A, and belonged to them, instead of you.
You- don't have access to wallet A, because it got deleted?

Do you perhaps have access from any previous adress that the 175BTC travelled through? I imagine the trail didn't start at wallet adress A- you must've bought them from somewhere. Another exchange?

[1]But;; if the case does not involve wallet B (You state: you need to prove you own the 175BTC that were coming from wallet A?) can't you just sign a message from wallet B, which has send 275BTC to (an exchange )
coming from wallet A?

This wouldn't prove you own wallet A, but it'd make it a lot more likely. I think it's the closest you'll be able to prove? Unless- i'm understanding this wrong, and they're accusing you of theft of the contents of wallet A (which were stored on the exchange) which you then withdrawed from the exchange and sent to wallet B?

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Why not? I think there'd be a much better chance of getting a jury/judge to understand such things when you hire someone from a company such as Chainanalysis, as opposed to representing yourself.

One solid evidence would be: showing Wallet A's master public key. But that involves showing all of your wallet's addresses and transactions.

By giving it to someone who knows Bitcoin, it will be possible to show that the change (UTXO) from that particular transaction was the one sent to WalletB because they were derived from the same SEED.
If the wallet isn't HD (Hierarchical Deterministic) or the used change address was just imported, this can't be used because anyone can just "import private key" to add the address to the wallet.

Providing the transaction ID alone isn't that solid IMO, it's too easy "fake" the change address by using "coin control" or "pay to many" option/command.

the only sure way that you can prove ownership of an address is by having the private key of that particular address and signing a message.

just receiving some coins from that address is not proof of ownership. so even if you show that address A has sent you 175BTC or even more transaction at other times, is not proving that address A belonged to you so you can't prove the transactions going out of that address were sent by you.
that would be like if someone sent you money via wire transfer and then you go to court trying to prove you own that other bank account just because it sent you money!