Recruitment of AMT

The tranquility of the city was suddenly broken by a series of murders. However, the perpetrator's methods were too sophisticated, and the three murder cases have not been solved so far. It was not until the fourth murder occurred that the police were sure that the four murders were committed by the same person. At the same time, someone discovered that the occupations of several deceased people matched a mysterious recruitment advertisement recently circulated on the Internet. What is this mysterious recruitment announcement about? Is this a coincidence or premeditation? In addition, the recruitment notice said that there are a total of 7 positions to be recruited. Will 3 more people be killed next...