with a fine-tooth comb

used to imply a very careful and thorough examination of something, often with great attention to detail and a focus on finding even the smallest flaws or errors

The idiom "with a fine-tooth comb" originated from the practice of using a comb with closely spaced teeth to search for and remove any tangles or imperfections in one's hair. Metaphorically, the phrase is used to signify a complete and detailed examination or scrutiny of something, leaving no room for oversight or missing even the smallest details.

The detective went through the crime scene with a fine-tooth comb, searching for any clues that could lead to the perpetrator.
The editor reviewed the manuscript with a fine-tooth comb, correcting grammar, punctuation, and ensuring consistency throughout.
The auditor examined the company's financial records with a fine-tooth comb, meticulously checking for any discrepancies or irregularities.
Before signing the contract, the lawyer advised her client to read it with a fine-tooth comb, ensuring they understood all the terms and conditions.
The researcher analyzed the data with a fine-tooth comb, scrutinizing every data point to draw accurate and reliable conclusions.