In March 2019, the Organisation for the Prohibition of Chemical Weapons (OPCW) published its final report on the April 2018 chemical weapons attacks in Douma, Syria (which we originally investigated in collaboration with the New York Times, in July 2018).

Since that time, the report’s conclusions have been challenged by a number of apparent ‘leaks’ from within the organisation. Yesterday, on 6 Feb 2020, the OPCW published the report of an ‘Independent Investigation into Possible Breaches of Confidentiality’, addressing those leaks.

In recent weeks, Forensic Architecture worked with Bellingcat to examine some of the spatial and material questions arising from one of those leaks. Today, we’ve provided an update our original analysis in light of this new material, and we’ve reproduced that update here:

The March 2019 report of the OPCW’s ‘fact-finding mission’ assigned to investigate the Douma incident (OPCW-FFM) included precise measurements of the size of the cylinders at Locations 2 and 4 (our sites 1 and 2, respectively), the size of the crater in the roof at Location 4 (our site 2), and dimensions of the spaces in which they were found.

Using these precise dimensions, we scaled and refined our models of both sites, using a technique called ‘image-matching’ to verify the dimensions provided in the OPCW report. Image-matching is a way of juxtaposing photographic evidence with spatial measurements.

In the process of image-matching, a given measurement is supported when a photograph is matched to a digital model from the same camera position, lens angle, and direction—as could be seen in the video above. Our image-matching of the available photographs from Location 4 supports the measurements of the cylinder and the crater that were provided by the OPCW-FFM report. (We also refined our model of the cylinder at Location 2, the balcony location that our original analysis called ‘site 1’. You can find updated digital models for both sites on our Github.)

In May 2019, an additional report leaks from within the OPCW, authored by Ian Henderson, a long-time employee of the agency, who refers to himself as a member of an ‘engineering sub-team’ within the OPCW-FFM.

The report argues that it was more likely that the cylinders were placed at Locations 2 and 4, than that they were delivered there by air. In part, this conclusion partially relies on Henderson’s assessment of the relative sizes of the cylinder and the crater in the ceiling at the Location 4.

Forensic Architecture and Bellingcat worked together to examine and compare the claims made by both reports about the (relative) dimensions of the cylinder found at Location 4, and the crater in the roof through which the cylinder apparently entered the room.

According to the OPCW-FFM report, the cylinder found at Location 4 was 1.4m in length. The report described the dimensions of the crater in the roof as 1.66×1.05m. The Henderson report does not independently define the dimensions of the cylinder, but provides the following diagram (from the Henderson report, Appendix 4, Figure 9), based upon a drawing from the OPCW-FFM report.

The diagram, which Henderson’s report says was produced for ‘illustrative purposes’, notes a scale of 1:10 at the top, but appears to have been photocopied and reduced in size, and is as such not provided to any clearly defined scale.

The diagram places the front of the cylinder over the edge of the crater, appears to support Henderson’s claims that this cylinder could not have passed through this hole. ‘it was not possible to establish a set of circumstances where the post-deformation cylinder could fit through the crater with the valve [the pressurised sealed opening at the end of the cylinder] still intact… and the fins deformed in the manner observed”’.

The Henderson report claims that its analysis was ‘conducted using sources of information available to the FFM’. However, if we follow the OPCW-FFM’s dimensions, there appears to be an error in the diagram included in Henderson report.

According to our analysis, if the crater in the diagram is 1.66×1.05m (as stated by the OPCW-FFM report), the cylinder drawn by Henderson would be approximately 1.48m in length; that is, 8cm too long. This difference, of almost 6%, is significant, since it challenges Henderson’s assessment that the cylinder could not have passed through a crater of the dimensions specified by the OPCW-FFM report.

Alternatively, when we scale the Henderson report’s diagram to the size of the cylinder as determined by the OPCW-FFM report — that is to 1.4m length — the dimensions of the crater are around 6 percent smaller than those provided by the OPCW.

Given that Henderson’s drawing has no scale or measurement we found that the proportion between the cylinder and the crater were drawn incorrectly: either the cylinder is drawn too large, or the crater too small.

We used our model of Location 4 to image-match cylinders of 1.48m and 1.4m in length. The study below confirms that the photographic evidence from Location 4 is consistent with a cylinder of 1.4m in length, and is clearly inconsistent with a cylinder of 1.48m. This image-matching process suggests that the Henderson report diagram has most likely exaggerated the length of the cylinder, and not the crater.

The Henderson report’s diagram superimposes over the crater an outline of the cylinder’s ‘harness’ in its damaged, deformed state. In this state, not only is the cylinder’s dimensions exaggerated but the cylinder and harness together have a larger ‘footprint’ than the state in which it would have impacted the roof.

This way of drawing is misleading: if the diagram is drawn to illustrate or test the hypothesis that the cylinder and harness could not have fitted through the crater, it should have taken into account the fact that the deformation would have been caused by the impact of the harness and the ceiling, and by the subsequent impact on the floor of the room below.

This study does not change our previous determination that the hole in the ceiling and the location of the cylinder on the bed do not easily align. It is possible that this cylinder was moved after arriving at the site from the air, as, our previous investigation showed, appears to have been the case at Location 2.