The phrase "am on case" is an informal statement that is commonly used to show that someone is committed to investigating or resolving a particular issue or problem. The antonyms for this phrase would be "not involved," "uncommitted," "unconcerned," "disinterested," "uninterested," "unresponsive," "passive," "indifferent," "negligent," and "apathetic." Each of these words represents a different level of disengagement or disassociation from the situation at hand. It is important to note that while these words represent a lack of engagement, they do not necessarily imply a lack of ability or competence. One can be disinterested in a situation and still possess the skills and knowledge necessary to resolve it.