The phrase "full investigation" means thoroughly looking into something to gather all the necessary information, facts, and evidence to understand a situation or problem. Full definition
The use of such a service balanced the goals of full investigation with administrative efficiency. (ngariss.com)
They require full investigation, research, fact - gathering, and proper preservation of evidence. (chrisearley.com)
Anifowose further stated that the State Government has swung into full investigation of the matter and would not hesitate to employ the full weight of the law to deal decisively with any unscrupulous developer who violates the law. (nigeriapoliticsonline.com)