How to make the (city) guards unable to track us?

Question

For a side quest we got job from a shady figure my character and two other player characters went to break into a smithy's home/workplace.

When we were in there our brute, low intelligence, tabaxi ranger took some new armor for himself dropping his current armor on the ground. When making our way out I disguised myself but rolled a horrible performance check when trying to convince two guards I was just strolling around with a box full of mushrooms.

We ended up killing the guards and fleeing. However the guards saw the faces of my companions and one of them left his personal possessions at the crime scene. Now, in a few in-game days we will be fighting in a public tournament and we will want to prevent being arrested on the spot.

Is there a way to make the guards unable to track us by our personal possessions and disguise my companions for a few days?

Extra information: we are level 4, the guards would have access to mages from a large institute I wouldn't really know what kind of magic they would have access to but the DM hinted at a spell to track a PC by his/her possessions. We are a rather magic deprived group with only one mage, two rangers, a rogue, and a barbarian. We do not have access to any relevant utility magic. The armor left was normal heavy armor and we did not kill all the guards we killed two and were able to use zephyr strike to dodge away from the other 10 that were called in by a horn.

Answer 1

Nondetection, disguises, and go to ground

Consider the spell Nondetection: a third level spell with an 8 hour durration.

For the duration, you hide a target that you touch from divination magic. The target can be a willing creature or a place or an object no larger than 10 feet in any dimension. The target can’t be targeted by any divination magic or perceived through magical scrying sensors. (PHB, p. 263)

Most spells that are used to find things (such as Locate Creature, Scrying, or Augury) are divination spells. The Nondetection spell does not only work against certain divination spells, or spells of a certain level: it simply stops them all. So even powerful wizards might be unable to circumvent it.

As a 4th level characters, you won't be able to cast Nondetection yourself. You'll need to hire a spellcaster to do so for you: ideally in some way that doesn't get you caught. That could be an exciting part of the next session, and it'll be entirely up to you DM how difficult it is to find someone willing or able to cast this spell for you. But if you can find some way to have this spell cast several times (once every eight hours), you'll be able to evade many of the magical means of tracking you. (And to metagame for a moment: if your DM lets you spend resources on hiring someone to cast Nondetection, you can probably expect that such an effort will be successful. If the DM wanted such a tactic to fail, they likely would just tell you that you can't find a spellcaster who knows that spell.)

As far as your physical descriptions go, you have indicated you have some means of disguising yourself. I'd recommend you continue to do so, especially at the public tournament. Maybe wear masks while competing: build up the "mysterious stranger" angle.

Keep in mind that none of these methods will be particularly helpful if you keep hanging out in places you've been seen before. Even if you are in disguise and magically shielded from scrying, don't be surprised if the guards come barging into the inn you've been staying at, having gotten a tip that you used to be there, and inspect all the guests, seeing if anyone is in disguise.