5 sentences

1. 警方认定他是单独作案。

   jǐng​fāng rèn​dìng tā shì dān​dú zuò'àn.

   The police determined that he acted alone.

   Source: Dong Chinese Dictionary

2. 他在星期六的晚上伺机作案。

   tā zài Xīng​qī​liù de wǎn​shang sì​jī zuò'àn.

   He waited for an opportunity to commit a crime on Saturday night.

   Source: Dong Chinese Dictionary

3. 现在，他在同一座城市连续作案两次了。

   xiàn​zài, tā zài tóng​yī zuò chéng​shì lián​xù zuò'àn liǎng cì le.

   Now he has struck twice in the same city.

   Source: OpenSubtitles

4. 他的指纹留在现场，这是他作案的铁证。

   tā de zhǐ​wén liú zài xiàn​chǎng, zhè shì tā zuò'àn de tiě​zhèng.

   His fingerprints were left at the scene, which is ironclad evidence of his crime.

   Source: Dong Chinese Dictionary

5. 警方打掉了一个专门在火车站作案的扒窃团伙。

   jǐng​fāng dǎ​diào le yī gè zhuān​mén zài huǒ​chē​zhàn zuò'àn de pá​qiè tuán​huǒ.

   The police busted a pickpocketing gang that specialized in operating at the railway station.

   Source: Dong Chinese Dictionary