4 sentences

1. 警方正在案发现场进行取证。

   jǐng​fāng zhèng​zài àn​fā xiàn​chǎng jìn​xíng qǔ​zhèng.

   The police are gathering evidence at the crime scene.

   Source: Dong Chinese Dictionary

2. 警方在案发现场附近发现了一件丢弃的凶器。

   jǐng​fāng zài àn​fā xiàn​chǎng fù​jìn fā​xiàn le yī jiàn diū​qì de xiōng​qì.

   The police found a discarded murder weapon near the crime scene.

   Source: Dong Chinese Dictionary

3. 警方正在对案发现场进行勘验，不放过任何线索。

   jǐng​fāng zhèng​zài duì àn​fā xiàn​chǎng jìn​xíng kān yàn, bù fàng​guò rèn​hé xiàn​suǒ.

   The police are conducting a forensic investigation of the crime scene, leaving no stone unturned.

   Source: Dong Chinese Dictionary

4. 警方在案发现场仔细搜寻，不放过任何蛛丝马迹。

   jǐng​fāng zài àn​fā xiàn​chǎng zǐ​xì sōu​xún, bù fàng​guò rèn​hé zhū​sī​mǎ​jì.

   The police searched the crime scene meticulously, not overlooking the slightest clue.

   Source: Dong Chinese Dictionary