4 sentences

1. 警方正在对此案进行深入侦查。

   jǐng​fāng zhèng​zài duì cǐ àn jìn​xíng shēn​rù zhēn​chá.

   The police are conducting an in-depth investigation into this case.

   Source: Dong Chinese Dictionary

2. 经过缜密侦查，警方揭开了这起共谋的真相。

   jīng​guò zhěn​mì zhēn​chá, jǐng​fāng jiē​kāi le zhè qǐ gòng​móu de zhēn​xiàng.

   After a thorough investigation, the police uncovered the truth of this conspiracy.

   Source: Dong Chinese Dictionary

3. 公安机关决定对这起合同诈骗案立案侦查。

   gōng'ān jī​guān jué​dìng duì zhè qǐ hé​tong zhà​piàn'àn lì'àn zhēn​chá.

   The public security organs decided to file a case for investigation into this contract fraud.

   Source: Dong Chinese Dictionary

4. 警方在侦查过程中，在现场发现了一些重要线索。

   jǐng​fāng zài zhēn​chá guò​chéng zhōng, zài xiàn​chǎng fā​xiàn le yī​xiē zhòng​yào xiàn​suǒ.

   During the investigation, the police discovered several important clues at the scene.

   Source: Dong Chinese Dictionary