The ladder was found propped up against the Lindbergh residence leading to Charles Lindbergh Jr.'s window


One of the main and most important pieces of evidence that lead to a conviction in the Lindbergh baby case was the ladder. The ladder was determined to be custom-built and experts who studied the workmanship claimed it must have been built by someone with working knowledge of its design. The fact that the ladder was custom-built meant that it would provide individual as well as class characteristics. Had a ladder been bought from a store in the area, it would not have been nearly as helpful in finding the kidnappers. Also, studying the types of wood that was used to build it could help narrow down which lumberyards and manufacturers process that specific type of wood.

Composition of the Ladder

The ladder was made of four different types of wood as opposed to one which could help narrow down the lumber mills the wood was bought from. In total there were six rails, eleven rungs and two dowels. Three of the six rails were North Carolina Pine; the last three rails and one rung were Douglas fir, and the other ten rungs were ponderosa pine. The two dowels used to fasten the three separate sections of ladder together were all birch (Koehler, 1937).

Wood Planer

Not only were many types of wood used in the ladder, the lumber from which the ladder was built also differed in that it had also been dressed by several different planers. A wood planer is a tool used for shaping wood; it flattens and smoothes the lumber and different machines will smooth the wood at different rates. It appeared as though the two bottom North Carolina pine rails had been dressed with a planer at the same lumber mill, and the cutting had left irregularities and identifying marks. It specifically had eight knives in the cutter head used for the surface and six in the cutter heads that dressed the edges (Koehler, 1937). They revealed individual characteristics due to a defective knife in the cutter head. These knives are periodically re-sharpened so only a certain number of shipments of lumber would contain this defective characteristic. The planer which was used for these two rails had a speed of 230 ft. per minute. Samples from twenty-three matching lumber mills were taken and were narrowed down and the two bottom North Carolina pine rails were traced to the M. G. And J. J. Dorn Company of McCormick, South Carolina. Arthur Koehler, wood expert, was able to trace a shipment of lumber from McCormick, South Carolina to the National Lumber and Millword Company in the Bronx. Also, the Ponderosa pine rungs had been shaped with a planer containing eight knives in one cutter head and six in each of the other three heads. This was a very unusual combination and it allowed investigators to narrow down those rungs as coming from one of only two mills that shipped to the New York area in 1931.

The top left-hand side board of the top section had four nail holes that were in the wood before it had been used as a ladder. Koehler determined that the wood had been taken from a source different from the other pieces used and was gathered separately when the other wood had run outiv. There was no wear and tear on this particular section, no rust forming around the nails from exposure to the elements and it was still a bright colour, indicating that its previous use must have been indoors instead of outdoors. Also, the type of lumber itself; a lower grade, is not typically used for such purposes and suggested that it would have been found to be part of a garage, a barn or attic (Koehler, 1937).

Ladder Measurements

Measurements of the rails and the lumber they were made from would prove to have significance for the case. They observed that two of the North Carolina pine rails had been dressed to 3 ¾ inches in width. Regular lumber is typically ¾ inch thick and 3 5/8 or 3¾ wide. These two pine rails had originally been 3 ¾ and had subsequently been narrowed down. The small difference in width observed helped narrow down the number of potential matching lumber carloads from 63 to 45 (Koehler, 1937).

Errors and Limitations

Many errors were made; more specifically with how the ladder was handled. The mishandling of evidence can interfere with the information that may be obtained. It is essential that photographs be taken of evidence before it is removed from the scene. The ladder failed to be photographed before analysis for evidence. Rationale for this was given that reporters would be arriving on scene and it would be difficult to protect. The first and most important thing that the first responding officer needs to do upon arriving at a scene is secure it. This would indicate that security was lacking and the scene not properly managed. The area had not been well taped off, which would have protected the ladder where it found against the house. Regardless, the ladder was brought inside the house in three separate pieces to be further analyzed (Fisher, 1973). This is when the photographs were taken. Any trace evidence (defined as a small or microscopic quantity of different materials that can transfer between people, objects and places for long periods of time), such as clothing fibres, may have been disturbed during transport. Also, whatever tools were used to break the ladder into its three pieces may have either interfered with tool marks left by the builders during construction of the ladder or have been confused as marks left by the builders. Evidence should not be tampered or touched until properly photographed.

Past vs. Present Forensic Techniques

  • Fingerprints can be found on almost any surface; whether latent or impressed into blood, dirt, etc. Recently, more advanced techniques have been used to detect fingerprints. Porous surfaces such as wood are typically difficult to retrieve fingerprints from, and therefore would have been challenging to find during Lindbergh’s time. A new device, called the Reflected Ultraviolet Imaging System has been developed to locate latent prints on most non-absorbent surfaces. When a UV light reflects the fingerprint, it reflects back, making it visible against the background surface (Koehler, 1937). During Lindbergh’s time, the only method available was powder treatments. The ladder was dusted but nothing was recovered. There may potentially have been latent fingerprints not discovered due to the limitations in forensic technology.

Wood Grain
  • Each piece of wood was microscopically examined by Koehler to determine its cellular structure. The grain of wood can vary, but the microscopic structure of cells and fibres of species of wood are always the same. Today, a comparison microscope with greater magnification capabilities would have been used, but would likely have yielded the same results. However, computer systems containing data on wood samples would have allowed for a quicker match. Similarly, microscopic views of the knife cuts were made to identify the type of planer used in dressing the wood.

Trace Evidence
  • Trace evidence on the ladder included some red paint. The paint was found to be the same kind used to mark lumber cargo, but the same colours weren’t always used. Today, that same paint would have been microscopically analyzed and compared to similar paint samples found on other pieces of wood, as well as other sources such as vehicles, for example. Paint is comprised of four parts; pigments, solvents, additives and resin. A stereoscopic microscope would have been used to compare samples side by side for colour, surface texture and colour layer sequence. Also, a Fourier Transform Infrared Spectrometer analysis would have been performed. With this examination, a laser beam of light is transmitted through a sample and a spectrum is produced. This will indicate how much light was absorbed by the paint at varying frequencies. Light spectrums are then compared to determine how similar the colours are.

Biological Evidence
  • DNA testing may also have contributed to the Lindbergh baby case had it been developed. Methods to find blood and other biological evidence have since developed. It appeared as though a thin shaving had been taken from the ladder with a pocket knife or chisel. Investigators hypothesized that it was taken to remove any evidence of injury which may have left some blood spots, yet there was no way to check for any biological evidence such as blood or bodily fluids. Luminol is one particular method for detecting biological substances on cleaned surfaces. The reagent will cause a blue glow. This substance will detect bloodstains that have been diluted up to 100 000 times.

Tool Markings
  • A comparison microscope would also have been very helpful in comparing the rail from the ladder with the wood found in Hauptmann’s attic floor. Investigators at the time used a crude method determining whether the two sources of wood matched by superficially examining photographs of the two pieces of wood superimposed on each other.
  • The irregularities in the surface of the lumber needed to be attributed to either manufacturing or because of the grain of wood. Instead of being observed microscopically, they were observed under different lighting conditions at acute angles.
  • Hauptmann was found to be in possession of tools that were potentially matches to tools used to cut recesses for the rungs. A chisel of the same width, and as being manufactured by a certain company about 40 years earlier as the suspects’ was found in his possession. There were also some saw cuts made in the recesses which were deeper than the depth of chisel. The widths of the saw cuts were determined and Hauptmann was in possession of two saws of the same width (Koehler, 1937).