形跡

1. Origins, structure, and basic meaning

• Structure: 形跡（けいせき） means a trace or sign suggesting that something happened.
• Basic usage: 開けようとした形跡があった refers to signs of an attempt to open a window, while 人が暮らした形跡 refers to traces of people having lived there.

2. Common pitfalls and similar expressions

• Traces versus evidence
  • 形跡 focuses on traces left behind; 証拠 focuses on grounds supporting a fact. The same trace may serve as evidence, but the words emphasize different aspects.
• The preceding action matters
  • In 開けようとした形跡, the important detail is an attempt to open something, rather than a statement that it was actually opened.