Best spells for detective work?

[Luccan]

I've had an idea for a character who uses magic to solve crimes... original I know. But in the context of D&D, there are a lot of spells to choose from and not all the most useful spells appear on the same class list. So, which spells would be most useful for an investigator and which lists do they appear on? The original idea was applied to a cleric, who gets useful things like speak with dead and zone of truth. What else would be useful when investigating a crime?

[Ninja_Prawn]

I'm playing a character (https://www.myth-weavers.com/sheet.html#id=691366) that does a bit of arcane crime-fighting and I've found the most useful spells are Minor Illusion (the gift that keeps on giving), Detect Magic and Identify. I expect Detect Thoughts will come in handy, but I haven't had it long enough to know for sure. Locate Object seems like a high priority, but I haven't been able to pick it up yet. Overall, her mundane skills (especially investigation, perception and all the Charisma skills) and noble background have been the most valuable things.

[Sigreid]

Knowledge cleric visions of the past power.

[JellyPooga]

Slightly tangenital to the topic, but Warlocks make great "investigators". In your typical investigation, time isn't as pressing as in your average dungeon delve, making the Warlocks Pact Magic really shine. When you have hours between scenes, your spell slots recharging on a short rest means you're able to bring out the big guns far more often than your usual spellslinger. Add tasty features like an invisible, flying "partner" who can get into tight spots (Chain Pact), plus Invocations that grant at-will use of things like Detect Magic,
Speak with Dead and Arcane Eye and you have a Class that's practically screaming to be a "Magic Sherlock Holmes".

More on topic, don't rule out Clairvoyance for remote observation and Invisibility (and similar spells, such as PWT and Gaseous Form) for "on site" observation undetected.

Have a mind to pick up the likes of Message, Sending and other communication spells (even Dancing Lights for signalling, in a pinch), because they're important for relaying information, checking facts or even calling in the heat if things go south.

[Breashios]

Don't overlook the feat Keen Mind in helping to realize the role you are seeking to fill.

[Galadhrim]

Don't overlook the feat Keen Mind in helping to realize the role you are seeking to fill.

Much like Adamat from the powder mage trilogy.

http://powdermage.wikia.com/wiki/Adamat

[Biggstick]

Most definitely Knowledge Cleric. You could dip three levels into Arcane Trickster or Bard for the Message/Mage Hand cantrip, Expertises, and a couple neat spell options (Find Familiar from AT or Comprehend Languages from Bard) but otherwise go Knowledge Cleric for 17 levels.

Knowledge Cleric specific spell list relevant to detective work: Identify, *Augury, Suggestion, Nondetection, *Speak with Dead, Arcane Eye, *Legend Lore, and *Scrying. (* are also a part of the standard Cleric spell list, but these spells will always be prepared for you as a Knowledge Cleric)

Cleric specific spell list relevant to detective work: Guidance, Detect Poison and Disease, Calm Emotions, Enhance Ability, Find Traps, Gentle Repose, Lesser Restoration, Locate Object, Protection from Poison, Silence, Zone of Truth, Clairvoyance, Dispel Magic, Feign Death, Meld into Stone, Revivify, Sending, Tongues, Water Walk, Control Water, Divination, Locate Creature, Stone Shape, Commune, Dispel Evil and Good, Geas, Greater Restoration, Raise Dead, Find the Path, True Seeing, etc. (Not going further then 6th level spells, as that's a bit ridiculous)

Knowledge Clerics also have what I consider a free way to read the surface thoughts of someone they're trying to interrogate. Their level 6 Channel Divinity says to simply spend an Action and choose a target to make a Wisdom save. If the target fails the save, you can read their surface thoughts. This Action of choosing someone doesn't imply the casting of any spells, meaning you can do this twice a short rest. If you decide to press your luck, you can "freely" cast the Suggestion spell on said target, and they automatically fail this Wisdom save. The only problem with this is that you will have to actually "cast" the Suggestion spell, meaning they'll probably know you're doing it.

Knowledge Cleric level 17 is also a pretty incredible ability if you're planning on being a detective. It's arguably a free modified Legend Lore spell once a short rest.

Clerics, and Knowledge Clerics in particular, are amazing at finding information. They have vast stores of knowledge to draw information from (represented by their two knowledge Expertises), they have a solid spell list to scout/acquire information, both their Channel Divinity options are great utility, and the class does all this without having to actually be any good (this character can effectively dump Charisma and still be good at finding information) at talking to people.