As the legend of Jack the Ripper from the nineteenth century continues up to the present day, this is perfect (no pun intended) situation where we can use the Present Perfect tense. Look at the present perfect examples highlighted in bold. Then read the explanations after the text. 
“Jack the Ripper” is the famous story of a mass murderer from Victorian London. He killed at least 5 women by slashing their throats and then cutting out their organs. As police have never solved the murders, this legend has fascinated the public for the whole of the last century. Researchers have put forward over 100 differrent theories as to the identity of the killer. The story has inspired numerous novels and movies. The real name of “Jack the Ripper” has been the subject of speculation since 1888. But now, experts believe that they have found the identity of the serial killer from the East End of London. Charles Cross, who was a cart driver, is the name of the most likely suspect. He claimed that he found Polly Nichols (the first murder victim) when she was already dead and was standing at the side of the road when more people turned up. However, a witness, Robert Paul told police that he saw Charles Cross crouching over Polly Nichols and he was touching the body. The experts believe that Cross was the killer and was disturbed as he was mutilating Polly Nicholl’s corpse. The author experts, Holmgren and Stow said that, “Cross hasn’t been the subject of much investigation and has appeared only vaguely in census records. We have found out that he gave a false name to police and his real name was Charles Latchmere. He walked past every single murder scene on his way to work and all the murders happened at the time when he would have been making that journey.”
Present Perfect Explained
Why do we use the present perfect tense in these sentences? Now, I’m sure you’ve all heard from lots of English teachers that the present perfect “connects the past to the present”, which isn’t really super helpful. In the Jack the Ripper story, the start of the tale is 1888 when the first woman was killed. That is our PAST. The PRESENT is now, i.e. September 2012. So let’s look at our sentences with those two times (1888-past & 2012-present) as our reference points.
PRESENT PERFECT EXAMPLES
1. Police have never solved the murders Or we could say… Police have not solved the murders from the time of the killings (1888) up until now (2012). So you can see that the time period that we are thinking of is ALL OF THE TIME from the past point (1888) UP TO & INCLUDING the present moment (2012). This is how the past time connects to the present time. It is an UNBROKEN, CONTINUING LINE OF TIME from the past action all the way through to the present moment. 2. This legend has fascinated the public Or we could say… This legend has fascinated the public from the time of the killings (1888) ALL THE TIME up until now (2012). Again, there is an UNBROKEN LINE, A CONTINUATION OF TIME between the past until the present. 3. Researchers have put forward over 100 different theories Or we could say… Researchers have put forward over 100 different theories from the time of the killings (PAST) up until now (PRESENT). 4. The story has inspired numerous novels Or… The story has inspired numerous novels from the time of the killings (1888) AND INCLUDING ALL OF THE YEARS/TIME INBETWEEN up until now (2012) 5. The real name of “Jack the Ripper” has been the subject of speculation since 1888 This sentence explains itself, doesn’t it? From the time of the killings in the past (1888) and including all the time up until now (2012) people have been speculating about Jack the Ripper 6. …experts believe that they have found the identity of the serial killer… This sentence uses a different time in the past – this past is NOT 1888… it is much more recent, more like last month, August 2012. This is like the classic textbook sentence, “I lost my keys, but now I have found them”. They are telling people the news (the new things). No-one new about the evidence, but now They didn’t have the evidence about the identity and then they discovered it (last month)… but they still have the evidence in their hands. There was a RESULT IN THE PAST and that RESULT IS STILL TRUE IN THE PRESENT. There is a continuing line of time of ‘HAVING the evidence’. They had it in the middle of August. They had it at the end of August. They had it at the beginning of September. They have it now . At no time did they lose the the evidence. From the moment of discovering the evidence, they have kept it.
Present Perfect v Past Simple
If the sentence was only… “They found the evidence.” (PAST SIMPLE) I would want to know WHEN they found it… OR what did they do with the evidence after that. So, it would be more normal to say the exact time when it happened… “They found the evidence on August 12th, 2012” (PAST SIMPLE) Or, what happened after that… “They found the evidence and then gave it to the police..” (PAST SIMPLE) USING THE PRESENT PERFECT version experts believe that they have found the identity of the serial killer tells us that at some point in the past (WE DON’T KNOW EXACTLY WHEN BECAUSE IT’S NOT IMPORTANT) the experts found the evidence and they still have that evidence NOW. 7. Cross hasn’t been the subject of much investigation and has appeared only vaguely in census records. Or…. Cross hasn’t been the subject of much investigation from the TIME OF OUR PAST (1888) AND ALL THE TIME UP TO NOW (2012). Just like sentences 1 to 5. 8. We have found out that he gave a false name to police This is the same explanation as for number 6. At some point in the PAST (WE DON’T KNOW WHEN) some action happened and NOW IN THE PRESENT TIME that action is still true. We are thinking about the PAST AND THE PRESENT TOGETHER & ALL THE TIME INBETWEEN WITHOUT ANY BREAK IN THE TIME PERIOD. I hope you can understand the present perfect a bit more clearly now – because I’m not going to write all of that out again!!! 🙂 Do you want to see something funny about the present perfect after all that studying?
