I, personally, would object to having to remove articles of clothing and to being searched. It is an invasion of privacy. If the store suspects you shoplifted something, they can't just pull you into a back room and do a strip search. Store security can detain you - nothing more than that. The store employee was wrong to do what he did.
Generally, an owner or employee cannot look inside a person's bag or purse without permission, unless they actually saw something being placed inside it, or if the item stolen is in plain view. The store owner or employee should contact the police if there needs to be further investigation, otherwise they should let the suspected shoplifter go. Any physical contact with a suspected shoplifter can lead to charges. If the suspected shoplifter is detained in a separate room, two employees, one of the same sex as the shoplifter, should be with the shoplifter, to avoid charges of sexual misconduct. There should be no action taken against a minor if a parent is not present, to avoid charges.
In addition, it is wise for an owner/employee to speak with the shoplifter privately and not loudly accuse the person of a crime in front of other customers, or speak rudely or offensively to the person, as charges of defamation can arise.
Most people will not sue because it is expensive to sue. If a storeowner handles shoplifters properly, it eliminates the risk of a suit, however.