If this is a crime, then any crime investigation should examine motive, timing and means.
Few recent geopolitical details to keep in mind:
1 - Trump administration just fired the #1 anti-Iran hawk (Bolton) and signaled interest in talking with "no conditions" with the Iranian regime. This would entirely change the Iranian position in the region [1]. It suggest lunacy from an otherwise calculating regime to jeopardize this potential new chapter.
2 - Iran just signed a $280 billion investment deal with China. Which includes presence of 5000 Chinese "security" forces. Essentially creating a Chinese military base across the waters from the US military base [2]. Iran would not want to escalate into a war before it has chance to land the Chinese forces on the ground and use them as a deterrent.
Do keep in mind, aside from the impact of the $280B investment in Iranian infrastructure and oil sector, it essentially makes Chinese currency the second currency of oil trade.
The oil trade in $USD is one of the most important and financial power that America has. This is something started during the Nixon era as a way to deal with the budget deficits needs of paying for the Vietnam war and it has continued ever since ensuing stability of $USD as we print money [3]
Just looking at these, you can make an argument there are multiple entities interested in either breaking any possibility of meeting between US and Iran, as clearly Trump has already walked backwards about "no condition" talk statements [4].
These entities with most to lose from a Trump/Iran meeting are:
Saudi Arabia Israel
Looking at the imagery and precision of these hits, you almost wonder if the attacks might have come from something else. Not to mention we've already had attacks on ships in the Persian Gulf with the original narrative disputed [5] and following a precision attack from a "flying objects" possibly a missile.
Given that the only evidence to Quds is a destroyed missile image from Saudi Arabia (a rather partial entity) from past and there are no actual evidence yet from the attack sites itself, you can as easily look at who has most to gain from a military confrontation with Iran or the very least stopping any diplomatic rapprochement between US and the Iranian regime. A case can be made for both Saudi Arabia and Israel.
Then there is the questions of the means.
On Israel there are multiple options.
1, Israel has some of the most stealth submarines in the world that they got from Germany. It is equipped with a cruise missile [6]
2, Israel can also strike from the air from a distance. Israel recently hit Iraq [7] and it has stealth ability to fly close to the Kuwait border to fire their cruise missiles [8]
The point I'm making, while you can make a case for Iran, you can as easily make the case for Israel. Given the biggest beneficiary of this latest escalation are probably the Israelis (please do not hate me for saying this) we should equally look at this possibility.
Lastly, these missile might have come for the "rebels" in Yemen. It's hard to imagine how an impoverished country could make something like this. Import the parts and everything else and then manufacture and test it. Obviously you could look at Iran as the source, however, there is one more regional player who benefits from the Saudi-Yemen war quagmire which is Qatar.
Saudi Arabia (or rather MBS) began a siege of Qatar and gave an ultimatum of invasion and overthrow of the country's rulers. Despite numerous back channel efforts there is no easing on the tension between Qatar and Saudi Arabia [9] A case can be made that Qatar would want to support the "rebels" and prolong the Saudi-Yemen conflict as long as possible to get leverage over the Saudis.
[1] https://theintercept.com/2019/09/15/threatening-war-oil-dona...
[2] https://www.middleeastmonitor.com/20190907-a-blow-to-washing...
[3] https://www.investopedia.com/articles/forex/072915/how-petro..., https://www.bloomberg.com/news/features/2016-05-30/the-untol...
[4] https://www.reuters.com/article/us-saudi-aramco-attacks-trum...
[5] https://www.reuters.com/article/us-mideast-tanker-japan-dama...
[6] https://www.nti.org/analysis/articles/israel-submarine-capab...
[7] https://www.aljazeera.com/news/2019/08/officials-confirm-isr...
[8] https://en.wikipedia.org/wiki/Delilah_(missile)
[9] https://www.trtworld.com/middle-east/saudi-qatar-hopes-for-m...