Philadelphia, PA  •  Pittsburgh, PA  •  Roaring Spring, PA  •  Chicago, IL  •  St. Louis, MO



Lesnevich & Detwiler owns and maintains one the most sophisticated private document laboratories in the United States.

Our fully equipped facility enables us to thoroughly examine signatures, writings, and documents. We also have the capacity to perform non-destructive forensic document examinations.

Additionally, the high quality court graphics we produce for judges, juries, and arbitration panels have become very well-known and respected around the world and are a cornerstone of our practice.


  • Handwriting, Hand Printing and Signature Examinations
  • Photography and Digital Imaging
  • Alterations, Obliterations and Erasures Examinations
  • Photocopiers/Facsimile/Office Machine Examinations
  • Mechanical Impression Examinations
  • Electronic Signature Analysis
  • Printing Processes Identification and Examination
  • Rubber Stamp and Seal Impression Examinations
  • Counterfeit Examinations
  • Fracture Match Examinations
  • Typewriter Examinations
  • Non-Destructive Ink Analysis
  • Non-Destructive Paper Analysis
  • Non-Destructive Indentation Analysis
  • Examinations of Chard or Soaked Documents
  • Restoration of Shredded Documents
  • Watermark Examinations
  • Evidence Handling Procedures
  • Expert Witness and Legal Proceedings
  • Examination Procedures


From identifying the handwriting of convicted murderers, to eliminating individuals such as billionaire, Mark Zuckerberg, and famed European artist, Peter Doig, on high value contracts and paintings.

Handwriting and signature examination is a pillar of our practice and comprises the majority of our casework.

The need for this type of service typically originates in cases where documents, such as anonymous and/or threatening letters, wills (and other testamentary documents), medical records, insurance policy forms, deeds, mortgages, checks (and other banking transaction documents), contracts and/or agreements contain disputed signatures and/or writings. These discrepancies can then become key pieces of evidence in a court proceeding.

Often, the identification, or elimination, of a writer may be (or may become) the ultimate issue in the case.

Although we are often retained to conducting handwriting authentication examinations, we also are routinely called upon to address questions pertaining to the authenticity of a document itself. In these situations, we may be asked to determine:

  • whether a page was substituted in a contract
  • whether all pages of a multiple paged questioned document were produced on a common machine or with the same printing technology
  • whether multiple ink formulas were used in the preparation of a particular entry
  • to identify covert security features that may be embedded in high value documents
  • to decipher portions of obliterated text (either with ink overwriting or some type of correction fluid, such as White-Out™)

Using state-of-the-art video spectral instrumentation (VSC6000/HS, VSC/400, and Regula 4305), we can meet the needs of our clients when confronted with these types of document authentication issues. If required, we do have the ability to offer these services in the field, as the VSC/400 and Regula 4305 are portable units.

In addition to the microscopic capabilities, the video spectral comparator (VSC) is a scientific instrument that allows an examiner to non-destructively examine and evaluate materials, such as inks and papers, beyond the visible light spectrum which is accomplished by employing light sources of different spectral characteristics, including long-wave and short-wave ultraviolet radiation, together with specialized bandpass filters.

The analyses are viewed and recorded using a high-definition camera system that is sensitive to infrared region of the electromagnetic spectrum. This further allows for reflected infrared absorption and infrared luminescence examinations and comparisons to be easily conducted when required.

The VSC enables an examiner to conduct a wide variety of non-destructive specialized examinations which provide further insight and evidence when tasked with determining the authenticity of a document, signature, and/or writing.

As mentioned above, VSC analysis is regularly utilized to non-destructively address a variety of factors specific to document authentication queries, including: ink analysis and differentiation; paper stock analysis; staple hole pattern comparison; watermark visualization and examination; indentation imaging and decipherment; ink-line/print intersection sequencing; latent image analysis; security feature detection and examination; as well as font and print process identification and comparison.



click image to open and download


click image to open and download

Regula 4305

click image to open and download

Electronic signature analysis is quickly becoming a routine part of the forensic document examination field. In a traditional signature examination, both the speed and the fluidity of a signature are interpreted by a document examiner in a subjective manner.

However, by conducting a complete examination utilizing the raw signature data associated with an electronically captured signature, these features can be numerically quantified with precision.

More specifically, electronic signature analysis allows an examiner to obtain exact timing and sequence data for each of the individual strokes and the exact construction of a signature itself.

This can be extremely valuable when examining a complex stylized signature. In addition to a pictorial examination of the signature, the acceleration/deceleration data can be generated and evaluated by an examiner in an electronic signature case, which can provide additional means of signature verification.

On November 3, 2011 in the case of American General Life Assurance Company of Columbus vs. Glenda Biles, et al., Federal Judge Tom S. Lee of the United States District Court, Southern District of Mississippi, Jackson Division ruled that the forensic analysis of electronically captured signatures does satisfy the Daubert requirements.

Furthermore, on April 30, 2013 the Fifth Circuit Court of Appeals issued a ruling which upheld the admission of electronic signature analysis testimony in that case.

Qualified Forensic Document Examiners must be able to render accurate and honest opinions and present the basis of their findings with effective court graphic illustrations (especially when providing courtroom testimony).

With decades of experience in the field, Gus Lesnevich and Khody Detwiler have extensive knowledge in examining evidence, preparing graphic illustrations, and giving testimony as court-qualified, forensic document examiners.

Much of their courtroom success throughout the United States and internationally comes from their ability to produce and present high quality court graphics to assist judges, juries and arbitration panels in clearly understanding the basis of their findings.

We also have the capabilities to obtain and produce high quality photographic images that can be used during our analysis and for providing testimony in the courtroom.

“That booklet [comparison chart] was one of the most effective juror presentations I’ve ever seen an expert use, in criminal or civil trials…and your testimony, on direct and cross, was well reasoned, patient, balanced – most important it didn’t sound at all like you were trying to favor [the client] – just letting the writing show what it showed.”

Indented writings found on the surface of documents can provide key evidence in determining a variety of issues including the sequence writings were completed on a document, sourcing documents together, dating documents, and/or revealing alterations that may have occurred in a document itself.

Indented writing can be deciphered though a number of methods including specialized lighting techniques (i.e., oblique lighting with a Foster + Freeman Crime-Lite®82L), as well as a Foster + Freeman Electrostatic Detection Apparatus (more commonly referred to as an “ESDA®” or an “EDD” examination).

The ESDA® analysis allows for an examiner to non-destructively develop and examine writing indentations (either visible or latent) that may appear on the surface of a document.

The physical results of the ESDA® analysis are encapsulated as “ESDA® Lifts”, which can then be used for further examination to sequence writings, to link the developed writing impressions to other documents and/or sources, or as demonstrative aide during live testimony in a court proceeding.

If required, non-destructive ESDA analysis can be conducted in the field with the portable ESDA® Lite.


Crime-Lite® 82L

click image to open and download


click image to open and download

ESDA® Lite

click image to open and download

The forensic examination and comparison of handwriting and signatures may require the aid of specialized microscopic laboratory equipment.

In the field of forensic document examination, having the capabilities to conduct microscopic examinations is essential.

We have the capabilities to conduct a variety of specialized microscopic examinations.

We also have the ability to capture and produce high quality microscopic images for further use during our examinations and as demonstrative aids when providing live testimony in court proceedings.

To strengthen our examination of signatures, writings, and documents, we have one of the most sophisticated private document laboratories in the United States.

This facility includes equipment to perform all aspects of non-destructive forensic document examinations.

We also have the capabilities to obtain and produce high quality photographic images that can be used during our analysis and for providing testimony in the courtroom.

Lesnevich & Detwiler has decades of experience in the field of forensic document examination. We can share our knowledge and expertise to training your staff so they can preemptively identify problems or potential problems before those problems become disasters.

Areas of training topics we cover include:

  • Signatures & Handwriting Analysis
  • Anonymous letters
  • And much more!


Complex examinations can be conducted most efficiently and effectively at our lab. However, we do have the ability to conduct on-site examinations if the situation warrants it.

In these instances, we can bring our expertise and specialized equipment to locations throughout the domestic United States. We can also set up shop at international locations as well.


Have any questions? We’d love to hear from you.