Methods and systems to identify log write instructions of a source code as potential sources of an event message of interest are described. Methods identify non-parametric tokens, such as text strings and natural language words and phrases, of an event message of interest. Candidate log write instructions and associated line numbers in a source code are identified. Non-parametric tokens of each event message of the one or more candidate log write instructions are determined. A confidence score is calculated for each candidate log write instruction based the number of non-parametric tokens the event message of interest and event message of the candidate log write instruction have in common. The candidate log write instructions are rank ordered based on the corresponding one or more confidence scores and the rank ordered candidate log write instructions and associated line numbers of the source code may be displayed in a graphical user interface.