an unfair punishment in school

is it legal for a school to suspend someone on something just because one party said they did it? my girlfriend who is a junior in high school in connecticut is being suspended because some kid lit firecrackers in school and then when he got in trouble he claimed my girlfriend did not i do not know if anyone else backed him up but the school has no solid proof that it happened are they allowed to suspend her just because he claims that? she needs school and has hardly ever done good in school until just recently and this may cause her to get grades that cause her to be unable to graduate. I hope someone can help this is very important to me. if this is not legal that they did this what would my next steps be, have her talk to a lawyer?

also i just found out two different people told them that she did it but that's only two there's no proof at all they called the police the police searched her and her locker i don't think that's right and now they are saying they plan to search her house as well. is any of this legal?

the school has every right to search the locker of any student because it is there property, which i also believe is extremely unfair but its ok to do. They can also search a backpack of another student which i do not believe in at all, that is the students property, not the schools, and while you may be on their premises, you are still forced to be there by law.

Fair? No.

Legal? Yes.