Tool Mark Investigations

Tool marks

Tools are often used by criminals to force entry to premises and can leave behind evidence for the forensic scientist to find.

Two tools of the same kind and made by the same manufacturer may look the same, but through use each tool can acquire differences. It is these differences that make them unique.

Forensic Scientists are able to help the courts convict criminals by matching the marks on tools to those found at crime scenes.


The examination of tool marks, as with other physical evidence, is based on two characteristics – class characteristics and individual characteristics.

Class characteristics are those characteristics that are common to a group of objects. For example, a hammer has a distinctive shape and typical size.

Individual characteristics are those characteristics which are unique to a given object. They are generally as a result of wear and tear or may be caused by isolated incidents during manufacture. For example, you buy a new pair of shoes and as you wear the shoes, over time you will get scratches and gouges on the soles. These marks are unique to your shoes.

Tool Mark Impressions

Caused by the interaction of two objects, tool mark impressions are distinguished in a variety of ways:

Static marks are made when the tool is pressed into a softer material and leaves an impression. A good example is a crow bar being used to force open a window and a subsequent impression is left in the softer surface of the wood. The Forensic Scientist will examine the marks and may be able to identify what type and size of tool caused the damage.

Dynamic marks are made when a tool slides or scratches across a surface. Think of a key being dragged along the side of a car; such an instrument leaves behind a pattern of lines or striations in the metal of the car. The pattern of striations may be enough for the examiner to identify a match with the tool belonging to a suspect.

Cutting marks are a result of pressure being applied at both sides of an object and are often associated with scissors, wire cutters or shears. When used these tools can leave behind marks and striations along the cut edges of the material.

Multi-stroke marks are caused by repetitive action, such as a saw moving back and forth.


The Scene Examiner will examine and photograph the tool marks in situ. If appropriate, the Scene Examiner will remove the object with the marks and take it to the lab for further analysis. If this is not possible they will make a cast of the marks, generally using a silicone rubber.

A tool may be recovered that is suspected to have caused the damage and this will also be taken to the lab for further analysis.

The Forensic Scientist will make test marks using the suspect implement. The test mark and the mark recovered from the crime scene will then be compared.

The Forensic Scientist will examine and compare the striation patterns using the comparison microscope. By comparing and matching the striations the scientist can prove whether the tool is responsible for the impression.

Tools can also have trace evidence, such as paint flakes adhering, or in the case of a human victim, blood or other body fluids. This evidence greatly assists in the investigation of a crime.

Investigators efforts when hired by attorney

Investigators efforts when hired by attorney

Coito v. Superior Court (2012), 54  Cal.4th 480    [dictum discussed witness statements and suggested efforts of investigator must reflect attorney initiative or thoughts]

2,022 Ranch, LLC v. Superior Court (Chicago Title Ins. Co.)
(2003), 113 Cal. App. 4th 1377  [“Chicago Title objected to questions to the adjuster Look concerning her interviews with third parties (the escrow company and the seller’s agent) as part of her investigation. These questions concerned her factual claims investigation and do not constitute attorney-client communications or attorney work product.”]People v. Collie (1981), 30 Cal.3d 43, at p. 59 [“Nobles also persuasively reasons that the privilege should extend not just to the attorney’s work product, but to the efforts of those who work with him to prepare the defense: “At its core, the work-product doctrine shelters the mental processes of the attorney, providing a privileged area within which he can analyze and prepare his client’s case. But the doctrine is an intensely practical one, grounded in the realities of litigation in our adversary system. One of those realities is that attorneys must often rely on the assistance of investigators and other agents in the compilation of materials in preparation for trial. It is therefore necessary that the doctrine protect material prepared by agents for the attorney as well as those prepared by the attorney himself.” (Id. at pp. 238-239 [45 L.Ed.2d at p. 154].) We conclude that the work-product doctrine applies to criminal cases and protects the work product of defense investigators.”]

Rodriquez v. McDonald Douglas (1978), 87 Cal.App.3d 626 at p.647-48

Southern Pacific Co. v. Superior Court (1969), 3 Cal.App.3d 195 at p.198 [ Protected per dictum not disapproved in Kadelbach ]

Mize v. Atchison, Topeka & Santa Fe (1975), 46 Cal.App.3d 436 at p. [Court assumed investigators reports were work product and compared them to expert’s reports but found waiver because the investigator was to testify ]

Brown v. Superior Court (1963), 218 Cal. App.2d 430 at p. 437

Suezaki v. Superior Court (1962), 58 Cal.2d 166, 178 at p. 177 [films taken by investigator hired by attorney solely for trial prep and intended to be confidential are work product but not privileged as a matter of law; court discretion must be exercised with qualified work product ]

William Monroe LPI, CCDI, CFSI


William A. Monroe is the Director of Investigations/Qualified Manager of W.A. Monroe & Associates Security Consulting and Investigations.  Monroe was born in Connecticut, and after graduating high school began a career in the Security Police Career field with the United States Air Force. During his time with the Air Force, he served in several law enforcement and Security capacities including canine handler, trainer, kennel master, Security force supervisor, Patrol supervisor, Desk Sergeant, Federal executive and dignitary protection detail supervisor, Special Investigations Joint Drug Enforcement Team member, Anti-Terrorism response team leader, and Department of Defense vulnerability and risk assessment team leader.  Bill is a diligent and highly skilled Security, Law Enforcement, and Investigations professional with a broad understanding of the criminal justice system. Bill is a consummate professional, with a proven track record investigating criminal, family law, and plaintiff negligence cases.  His passion for the Constitution and the legal process, coupled with his strong desire to seek out the truth in every case are unparalleled.

Bill is a California Licensed Professional Investigator with over 10 years of professional investigative experience, ranging from insurance fraud investigations, felony three strike cases, to capital murder cases.  Bill is an expert in criminal defense investigation and specializes in capital case mitigation, police procedure and use of force, K-9 search and seizure, and K-9 narcotics and explosives detection. He has superior investigative abilities coupled with comprehensive skills in forensic interviewing, forensic photography, crime scene examination, blood spatter detection, recognition, and analysis, and preparing and presenting accurate facts.

          Bill is a Criminal Defense Investigation Training Council (CDITC) board trained and certified Criminal Defense Investigator CCDI.  He is also a CDITC board trained and certified Forensic Science Investigator (CFSI).   He is currently pursuing his certification as a CDITC board trained and certified Forensic Interviewer (CFI-FTER).  Monroe completes 12-24 Continued Learning and Education (CLE) credits per year.
          Bill  serves on the faculty and training advisory board as the CDITC Western Regional Director and is a faculty cadre Instructor for the Criminal Defense Investigation Training Council (CDITC), Center for Investigative Studies.
          He holds an Associates of Science degree (AS) from the Community College Of The Air Force in Police Science/Industrial Security.  He holds a Bachelors of Arts (BA) degree from Ashford University in Social and Criminal Justice.  Bill  is currently pursuing a Masters of Science degree (MS) in Criminal Justice with a specialization in Forensic Science from Ashford University with 22 credits remaining.

Our Responsibility to Mentor


Good Evening defenders!

Our responsibility to teach, and more importantly mentor each other is imperative to upholding the highest standards in Criminal Defense Investigations. How better to encourage dialogue between professional defense investigators and share investigative philosophy, methodology, and principles in our specialty field. One of the things that discouraged me from the specialty of defense investigation in the beginning of my career was the lack of willingness from “Experienced” investigators to mentor me and show me the specifics of defense investigation. I could find any number of investigators that would tell me why they were the best investigator in the state of California, or the best investigator in the country. It was very easy to find investigators that would tell me what a terrible investigator so and so was, and how much better they were than the other guy.

One of my favorite quotes is from Benjamin Franklin he said, “Tell me and I forget, teach me and I may remember, involve me and I learn.” I was fortunate enough early in my decision to focus primarily on defense investigation, to happen across some very good defense investigators that were not only willing to teach me the science of defense investigation, but they helped me to understand the methodology of sound defense investigation. They showed me through example how to conduct my investigations in an organized, methodical, ethically responsible and procedurally sound manner.

Imparting your knowledge, experience, and thought process only makes you better and your peers better investigators. Continuing to challenge each other, teach and learn from each other is paramount in our efforts in maintaining the tradition of intellectual and academic exchange in an atmosphere which emphasizes innovation, and promotes new learning.

So ask yourself. Which type of investigator are you?

CDITC Forensic Science Investigators Academy

Good morning Defenders!

Back to work after an intensive week long certification/training, for my certification as a Certified Forensic Science Investigator (CFSI). The Academy, hosted by the Criminal Defense Investigation Training Councils Center for Investigative Studies (CDITC), was one of the best I have attended. I found the course to be, informative, concise, and interactive and would recommend it to any Licensed Professional Investigator, or Specialty Investigator, who would like to learn the ability to interpret and recognize the need for independent expert analysis, facilitate the efforts of forensic science experts, and incorporate the findings of those experts into the investigative process to advance defense theory development. I am honored and extremely excited to have been invited to become a part of the CDITC Faculty and Training Advisory Board. I feel it is imperative as specialists in our field, that we promote excellence through mentoring, training, peer reviews, seminars, and conferences, promoting expert knowledge and expertise within the discipline of criminal defense investigation. There is an art, and science to this.

However, contrary to what some of us may think, or say to each other, everybody is not good at EVERYTHING. You know the guy or gal, the one who will tell you they are an expert at everything. Surveillance, “I’m an expert”. Backgrounds “I’m an expert”. Domestic, “I’m an expert”. Criminal Defense, “I’m an expert”. I tell people all of the time, I may not know EVERYTING but I know a whole helluva lot of stuff about SOME things. I am an expert in Criminal Defense Investigation; My specialty is capital case mitigation, police procedure and use of force, K-9 search and seizure, and K-9 narcotics and explosives detection. I am a facilitator I can make large scale investigations, with multiple investigators, witnesses, and moving parts go. I can bring a team of different individuals together and galvanize them around a central goal. I am a specialist, a warrior, a gladiator, in search of the truth. Although I cannot be the best at everything, I do have a pool of over 300 CCDI’s in the world stretching from Guam to London at my disposal who are experts in just about anything I will ever need. If I can’t do it I know a Guy, or Gal who can. I also know that the professional Board Certified Criminal Defense Investigator shares my same philosophy, my same methodology, and the need to standardize and develop an investigative philosophy and methodology specific to the discipline of criminal defense investigation. If you are not utilizing your fellow Investigators in your cases, you should be. The goal should always be to provide the client with the MOST comprehensive, impartial, search for the truth we can provide them. Be safe Defenders!



1) The criminal defense investigator will adhere absolutely and unconditionally to the objective and impartial search for truth. He will abstain from involvement in any situation that subverts this professional commitment.


2) The criminal defense investigator will refrain from asserting, in any professional capacity, any beliefs, opinions, or biases regarding any person or situation under investigation, prior to having commenced the investigation. Nor will the investigator permit any pre-established beliefs, opinions, or biases to influence the course of an investigation to be undertaken.


3) The criminal defense investigator should never, as a matter of policy, claim to have attained absolute or conclusive truth regarding the scope of any investigation. As a matter of policy, investigative truths should always remain potentially open to reinterpretation as new facts or theories emerge. In principle the investigative process should remain speculative rather than dogmatic.


4) The criminal defense investigator will be absolutely and unconditionally honest in all reporting to clients. The investigator will make no dishonest representation of any fact, issue, or theory relating to any case for which he is responsible.


5) The criminal defense investigator will be truthful and open in all communication to colleagues and the public, except in so far as such communication may compromise client confidentiality


6) The criminal defense investigator will honor, absolutely and unconditionally the confidentiality guaranteed to every client, supervisor, or colleague.


7) The criminal defense investigator will not violate any law during the performance of his professional responsibilities.


8) The criminal defense investigator will refrain from any professional activity that jeopardizes health or safety of another person.


9) The criminal defense investigator will refrain from any commitment that entails any inappropriate conflict of interest.


10) The criminal defense investigator will not engage in the unauthorized practice of law or represent himself/herself as a law enforcement officer.