【摘要】 足迹是犯罪现场最常见的痕迹之一,尤其是单个足迹和残缺足迹。以往公安系统对其提供的罪犯信息利用率很低,还停留在凭经验进行目估尺测的阶段。本文是在[1]、[2]、[3]对成趟步幅特征定量化统计检验方法的基础上,对单个足迹或残缺足迹,找到了主要特征指标;对这些特征指标研制成功了定量化测试的仪器;提供了检验的统计方法。经三年多来的反复试验,已取得成功,并用于实际破案,为刑事技术增添了新的破案工具,已于一九八七年四月通过了部级鉴定。更多还原

【Abstract】 It is very probably for criminals to have their characteristics of footmarks left in the crime scene. But the investigators make little use of it. They simply analysed and compared the features of footmarks by experience. In the references （1）, （2）, and （3）, we had presented successfully four statistical methods for testing characteristics of step magnitude. On the basis of above methods, this paper presented a new statistical method for testing characteristics of solid footmarks, it had gained success in many occasions. At first, in the plaster models of the solid footmark Descartes coordinate system was established. In coordinates, point （0, 12） （length in unit of CM） at the fore sole of the foot （not thumb） was chosen as the centre. Height of the point in the plaster model was measured, and recorded as h₀ （height in unit of MM）. A special instrument was used to measure the height. Then we chose points （0, 13）, （0, 11）, （-1, 12）, （1, 12）, （1, 13）, （-1, 13）, （-1, 11）, （1, 11）, and called them as middle points. Their heights were noted as h’₁, h’₂, h’₃, h’₄, h’₅, h’₆, h’₇, h’₈ respectively. Similarly （0, 15）, （0, 9）, （-3, 12）, （3, 12）, （3, 15）, （-3, 15）, （-3, 9） and （3, 9） were called as marginal points, their heights were noted as h₁, h₂, h₃, h₄, h₅, h₆, h₇, h₈. By testing, it was indicated that h_O, h_j and h’_j （j=1, 2, …, 8） all had normal distribution. Let g_j=h_O-h_j, Then g_j obviously had normal distribution. The values of this variable of the criminal and the suspect were noted as g_Oj, g_ij （i=1, 2, . , n, n is number of suspects） respectively. Suppose g_Oj～N (μ_Oj, σ_Oj²), g_ij～N (μ_ij, σ_ij²). The results obtained by testing 2000 footmarks of 20 persons （100 footmarks per person） indicated σ_Oj²=σ_ij²σ₁², i=1, 2,…, n; j=1, 2, …, 8. σ₁²= 1. 12 was obtained from 2000 data. Hence g_Oj-g_ij～N (μ_{Oj-μij, 2σ1²} , Under hypothesis H_O: μ_Oj-μ_ij=O, g_Oj-g_ij/2^1/2σ₁ ～N （0, 1） Therefore C_1i sum from j=1 to 8 (g_Oj-g_ij/2σ₁² ～x²（8） For α given, there is P(C_1i>x_α²（8）)=α, That is, statistic C_1i can be used to test hypothesis H₀. Similarly, the statistics C_2i, and C_3i, of characteristics at the fore sole and thumb of the foot are constructed respec- tively, C_2i, C_3i have Chi-square distributions with 8 and 5 degrees of freedom respec- tively. If C_1i≤x_α²（8）, C_2i≤x_α²（8）, C_3i≤x_α²（5） happen at the same time, then the suspect and the criminal have same characteristics of the footmark, otherwise, the suspect can be eliminated. At last, this paper gives a practical example,更多还原