Why was Jack the Ripper was never caught?

Answer 1

It was not for the lack of trying. Scotland Yard was desperate to catch the Ripper. And they spared no expense to bring the fiend to justice. In the 1880s forensics were an unknown. At the time there was not even a test that could tell human blood from animal blood. Fiber and hair analysis didn't exist. Criminal profiling was a century into the future. Fingerprints did exist at the time but it would be decades before it was actually used with any consistancy.

So Jack The Ripper was left to his own devices. He continued to terrorize London's east end for years after he was thought to have stopped.

Answer 2

He was not.