Rebirth：I become the murder who has killed 40 persons

Alex suddenly discovers that his surroundings gets extremely strange after he woke up this morning and he realizes that he has an amazing experience of time-and space travel.
There is only a diary beside him and he thinks that maybe this diary would answer his current confusion.
However, when he opens that diary, he finds that the contents of that diary are extremely crazy and it is clearly a record of crimes, including at least 40 cases. And It's 90% sure that original owner is that murder, which makes Alex totally shocked.
Just when Alex is about to read carefully and figure it out , the piercing siren downstairs wakes him up.
Do the cops come here to catch him? will he surrender himself? Did the original owner really disappear? Or should he at least try to survive? What he should do exactly then?...
Thousands of memories have come to Alex's mind...