## 1 Introduction
[6] conducted a study using lead bullets fired from a 0.177\({}^{\prime\prime}\) (4.5 mm) caliber air rifle on glass windows of varying thicknesses (3, 4, and 5 mm), including both regular glass plates and those coated with thin Sun Control  
Figure 1: Cases of modified slingshots and glass damage by slingshots. (**a**) Enhanced slingshot (Republic of Korea, 2023); (**b**) semi-automatic slingshot (Republic of Korea, 2024); (**c**) criminal case (Republic of Korea, 2023). (Source: photographed by the authors.). Film (SCF). Their findings revealed consistent damage-hole diameters across all glass types, ranging from 4.77 to 7.5 mm, as verified by the chi-square test. No significant differences were observed in fracture patterns between SCF-coated and uncoated plate glass, regardless of which surface received the impact. [PERSON] et al. [7] examined multiple fracture patterns in glass plates of different thicknesses by vertically launching round nose pellets from an air rifle at a fixed range. Visual inspection revealed distinct chip patterns: circular for 3 mm glass, oval or triangular-edged for 4 mm glass (both transparent and privacy types), and irregular for 5 mm glass. Hole diameters ranged from 4.1 to 6.7 mm. The authors noted that hole patterns and glass shard characteristics varied significantly between standard firearms and air rifles, suggesting that weapon type could be inferred from analysis of hole diameters in damaged glass. [PERSON] [8] examined the distinctive impact pattern of a glass plate collided with fully jacketed bullets fired by an AK-47/56. High-velocity bullets created clean, round holes with outward beveling on the exit side of glass sheets, while crack branching or bifurcation occurred only under sufficiently high applied stress. [PERSON] et al. [9] examined the fracture patterns created on window panes of varying thicknesses when struck by 0.177\({}^{\prime\prime}\) (4.5 mm) lead pellets with round nose and flat nose. The research revealed that both pellet shapes produce consistent hole diameters across the tested samples. [PERSON] et al. [10] performed soft body pendulum impact tests and numerical simulation analyses to assess the structural safety of glass panels. The study uncovered that the flexural strength of the glass material marginally exceeded code specifications, while energy loss escalated with increasing release height until the glass panel fractured. Despite the valuable insights provided by previous studies on glass fracture patterns caused by various projectiles, a significant research gap exists regarding the specific impact of steel balls fired from slingshots. Previous research has primarily focused on analyzing glass fracture patterns resulting from high-velocity projectile impacts, typically using gas compression systems or rifles. However, there is a notable gap in the literature regarding the fracture patterns of glass when subjected to low-velocity projectiles, such as those fired from slingshots. This gap is particularly crucial in the field of forensic engineering, where understanding the unique damage patterns caused by slingshots is essential for accurate crime scene analysis and reconstruction. To address this research gap, our study investigates glass damage patterns resulting from steel balls with diameters of 8 and 10 mm, which are commonly used in slingshots. By conducting approximately 30 controlled shots and analyzing the resulting damage patterns on 5 mm glass, we aim to generate valuable data for forensic investigators. Furthermore, we explore the potential for identifying collision velocity and steel ball diameter based on observed damage patterns. This research seeks to contribute to the expanding field of forensic ballistics and glass fractography, offering critical insights for law enforcement agencies and forensic experts handling cases involving slingshot-induced glass damage.