To quote the PHB:
Lawful Good: A lawful good character acts as a good person is expected or required to act. She combines a
commitment to oppose evil with the discipline to fight relentlessly. She tells the truth, keeps her word, helps those in need, and speaks
out against injustice. A lawful good character hates to see the guilty go unpunished. Alhandra, a paladin who fights evil without mercy
and who protects the innocent without hesitation, is lawful good.
Lawful good is the best alignment you can be because it combines honor and compassion.
Neutral Good: A neutral good character does the best that a good person can do. He is devoted to helping others. He
works with kings and magistrates but does not feel beholden to them. Jozan, a cleric who helps others according to their needs, is neutral
good.
Neutral good is the best alignment you can be because it means doing what is good without bias toward or against order.
Chaotic Good: A chaotic good character acts as his conscience directs him with little regard for what others expect of him.
He makes his own way, but he's kind and benevolent. He believes in goodness and right but has little use for laws and regulations. He
hates it when people try to intimidate others and tell them what to do. He follows his own moral compass, which, although good, may
not agree with that of society. Soveliss, a ranger who waylays the evil baron's tax collectors, is chaotic good.
Chaotic good is the best alignment you can be because it combines a good heart with a free spirit.
So I think it really depends on the situation. It's not a question that can be answered Yes or No.
LG: The Paladin believes this person is a murderer and is asking where this person's cronies are. The laws of the land dictate that any measure that brings about justice can be used. So this "torture," as some of you have put it, is not illegal in this land. The Paladin is doing his/her best to bring a murderer to justice. In this case, strictly ruleswise no, it's not an evil act.
NG: Pretty much the same, but the character is doing the best he/she can do to bring a killer to justice.
CG: Does what they want.
It's all situational. It also all depends on the moral compass of the DM. If the DM thinks that is torture, than odds are it will be considered an evil act in game. If the DM understands why it's being done, odds are it won't be.