| Nominativ | investigatio, investigationeque, investigatio | investigationes, investigationes |
| Genitiv | investigationis, investigationis | investigationium, investigationum, investigationium, investigationum |
| Dativ | investigationi, investigatione, investigationi | investigationibus, investigationibus |
| Akkusativ | investigationem, investigationem | investigationes, investigationes |
| Ablativ | investigatione, investigatione | investigationibus, investigationibus |
| Vokativ | investigatio, investigationeque, investigatio | investigationes, investigationes |
