Chemical Analysis of Swabs

• In the swabs from the fragments (item 1) and from the swabs indicated in item 15, the amounts of nitrate ion and ammonium ion (about [illegible] g) slightly exceed the natural background level.
• Nitrate ions and ammonium ions are usually present in the traces of an explosion of mixed explosives containing ammonium nitrate as a component.
• On the other hand, substances of organic and inorganic nature are widely used in everyday life and in the national economy, which either directly contain the above-mentioned ions (for example, ammonium nitrate fertilizers) or form them in the process of their decomposition (for example, aniline dyes, nitro-lacquers, etc.).
• It is not possible to unambiguously determine the origin of the detected ions based on the results of physicochemical studies.

Detection of Combustion Products

• In order to detect condensed combustion products of inorganic components of explosives and pyrotechnic compositions (for example, aluminum, magnesium) or their unburned particles, studies were conducted on deposits of inorganic substances on paper filters remaining after filtration of the swabs.
• The studies were carried out by the EPMA method on a JSM-840 scanning electron microscope from "Jeol" (Japan) with an ISIS microprobe analyzer from "Oxford Instruments" (UK) according to standard methods.
• Accelerating voltage — 20 kV.
• Determined elements — from beryllium to uranium.

Sample Preparation

• Preparation of samples for the study of deposits on filters was carried out as follows.
• Each of the filters was placed in a test tube with alcohol and subjected to ultrasound to separate particles from the filter surface and from each other.
• After that, the alcoholic suspension containing microparticles was applied to the surface of the stage of the electron microscope.
• After the suspension dried, the microparticles were present on the surface of the stage in the form of a monolayer.

Results of Particle Analysis

• As a result of the study, particles with sizes from 2 μm to 15 μm, each having a shape close to spherical, were found on the surfaces of the filters with swabs from the fragments (items 1 and 2) and swabs (item 15).
• The chemical basis of the particles is aluminum oxide with impurities of magnesium, silicon, calcium, and iron.
• The formation of aluminum oxide particles of spherical or near-spherical shape occurs during the combustion or explosion of aluminum-containing explosives or pyrotechnic compositions.
• The presence of these particles on the filters allows for the conclusion that aluminum was most likely part of the explosive charge.

Conclusions from Physicochemical Studies

Based on the physicochemical studies conducted, the following conclusions can be drawn.

• As the explosive charge, either a mixed explosive was used, which included TNT, hexogen, and, most likely, aluminum, and in addition, ammonium nitrate or a combination of the above-listed substances and explosives based on them could have been included.
• It is not possible to establish the specific brand of the exploded explosive from trace amounts. For this reason, it is not possible to determine the area of application of the above-mentioned mixed explosive or the explosives that were part of the combined charge.

Explosive Technical Studies

(conducted by expert T. V. Vinogradova)

To answer questions 1, 2, and 5 of the decree, the expert studied the materials of the previous sections, the protocol of the inspection of the scene of the incident dated September 16, 1999, with appendices, video material filmed at the site of the explosion, the protocol of the inspection of objects dated September 20, 1999, with appendices, the interrogation protocol of suspect A.I. Iskanderov, and the interrogation protocol of witness V.V. Iskanderova.

Scene Analysis

• As follows from the video recordings and the protocol of the inspection of the scene, in front of the 4th entrance of house No. 35 on Oktyabrskoye Highway, there is a crater in the ground with a depth of 3.5–4 m and a diameter of 13.5–15 m.
• Also, within a radius of several hundred meters from the crater, the glazing, window frames, and door frames in residential buildings and other structures were partially or completely destroyed.
• These destructions are the result of the action of an air shock wave formed during the explosion of a concentrated explosive charge.
• At the same time, the location of the crater corresponds to the location of the charge.

Vehicle Fragments

• According to the protocol of the inspection of the scene dated 16.09.99 and the protocol of the inspection of objects dated 20.09.99, fragments of parts of GAZ-53 and PAZ-3205 vehicles were found at distances of up to 430 m from the crater.
• As can be seen from the photographs provided (appendix to the protocol of the inspection of objects), the fragments found have deformations characteristic of explosive impact.
• It follows from this that the explosive charge was located either in the immediate vicinity of the indicated vehicles or inside them.

Charge Mass Estimation

• The estimation of the mass of the exploded charge was carried out based on the partial destruction of glazing recorded in the protocol of the inspection of the scene at the house most distant from the site of the explosion (about 700 m), house No. 56 on Koshevoy St.
• For the calculation, Sadovsky's formula for a surface explosion was used (Pokrovsky G.I. Explosion. M. "Nedra" Publishing House, 1973):

$$\Delta P = 1.06 \cdot (\sqrt[3]{G} / R) + 4.3 \cdot (\sqrt[3]{G^2} / R^2) + 14 \cdot (G / R^3)$$

Where:
* $\Delta P$ — pressure jump at the shock wave front, atm;
* $G$ — mass of the explosive charge in TNT equivalent, kg;
* $R$ — distance from the site of the explosion to the object of interest.