I work in mortgages and have done loads of anti money laundering training. Bear in mind that I'm British and the law may be different over here.
Here's the scenario: MC's wife is killed, and MC is now murder suspect. Video footage points to someone else actually doing the deed (physical characteristics don't match the MC), so now it's a possible murder-for-hire scenario.
my q's:
- what kind of financial records do police examine?
They can request financial records from the bank and will work closely with the bank's anti-money laundering department. They can investigate records of financial transactions and documents supplied to the bank to determine if any of them are evidence of money laundering.
- is there a specific person who does the examining (e.g. forensic accountant?)
The bank will have an anti money laundering department (it may not be called this, it may have some cryptic sounding name and the bank will never let a customer know that anything of theirs has been referred to it).
The police will have dedicated officers for investigating money laundering.
- how long would investigation of financials take, and how far back would the records need to go?
The police and AML department will investigate the whole audit trail if necessary. How long it takes depends on how dodgy everything is. They will keep collecting evidence until they have enough for a conviction. They won't let the person know that their account is under investigation and it's illegal for bank staff to tell them (that's tipping off and can result in 2 years in jail, because it's possible that if you're alerting potential suspects to this, that you're in league with organised criminals and warning them about it) plus it's shitty customer service "oh yeah, we think you're laundering money" lol.
- if additional evidence is taken from MC's home and office, such as computer equipment - does this equipment ever get returned to the MC if nothing incriminating is found on it? if returned, what's the typical timeline?
The police will return confiscated equipment if nothing incriminating is found. Bear in mind that they won't usually need to confiscate anything from someone's home/computer to investigate money laundering. The audit trail (including any fake documents that have been given to the bank to make their audit trail look legit) is with the banks, etc.
- how much access to MC's finances do police have? e.g. are they able to get account numbers, and actual $ amts, or is it more general, like: have there been any transfers/withdrawals of >x amt over y time?
They can request whatever info or documents they need from the banks AML department.
Looking at your scenario, if he's paid a hitman, it's not going to be the kind of transaction where the hitman gets paid right into his bank account. The hitman would take the money in cash and there'd be no audit trail beyond the husband making (a) large cash withdrawal(s). I, personally, would not buy it at all if someone paid a hitman directly into his bank account via online banking. Anyone who's involved enough in organised crime to be a hitman isn't going to be that stupid.
If the police suspect that the person who did the murder is a hitman, and they know who he is, they could investigate his accounts for evidence of money laundering, but if they don't know who did it, they can't do this.
The police could ask the bank if the husband withdrew a large amount of cash prior to the murder, but as it would be cash, they wouldn't be able to link it directly to the hitman. It's circumstantial evidence only.
Also, in your scenario, I'm not sure why the police would think it was a hitman just because someone else did the murder, not him. They'd need a good reason to suspect the husband of hiring a hitman. They wouldn't think "someone else did the murder let's see if the husband paid a hitman" without some other compelling evidence that he may have done this. At this point if they have such evidence, they may well go to the bank and see if he'd made any large cash withdrawals.
Maybe they already found out that he'd made a large cash withdrawal from his bank account, e.g. they found several receipts from ATMs on consecutive days showing him withdrawing the maximum amount of cash each time. That would be a pattern of transactions that would warrant investigation - but hiring a hitman is only one possible reason. It could be that someone was blackmailing him and his wife was murdered by the blackmailer. Even if hiring a hitman was what happened, they already have as much of the audit trail as they're ever going to get with the ATM receipts and won't need to go to the bank for more. Plus there may be a totally legal, legit reason for someone withdrawing loads of cash - it's not illegal to use cash for transactions, however large.
hope that helps
Please bear in mind the Britishness of my answers and that my job involves mortgages, and I don't work for the police or in the company's AML department.