My landlord has lied to me multiple times and I have proof that he has lied. Is that illegal? I live in Utah. If so, could you please direct me to the law that says it is illegal?
Lying in itself ("of course you will get a wifi signal here") is not a crime. However, if you have proof that the lies were intended to benefit your landlord at your expense ("You won't sign the lease unless there's wifi? No problem") and that they actually did so ("You've signed the lease, it's too late to back out"), he may be guilty of fraud, which is a civil wrong and may be a crime.
You would be well advised to consult a lawyer before going amy further, since there are probably ten people believing themselves to be victims of fraud for every one who actually is so in legal terms. The lawyer will also probably tell you that the best you can hope for is restoration to the state before the lies (in my example, the lease is cancelled and you get your deposit back), though the authorities will look at prosecuting the landlord.
Your landlord must fulfill their obligations under the lease and local tenancy law. Those obligations would generally not include an obligation to tell the truth.
If they are lying to avoid their obligations then the lying is not unlawful, the avoidance of the obligation is.