Two items prove this. 1) the gap of 40 days between kills. The ripper couldn't find a victim in 40 days?! There were hundreds of prostitutes in Whitechapel. NO. The number 40 is significant to the killer. Jesus spent 40 days in the wilderness. The Jews travelled for 40 years in the desert. Jews.
2) The Goulston Graffito. "The Juwes are the men that will not be blamed for nothing". A tongue twister that blames the killings for the jews. A blood soaked piece of cloth was found close by.
The killer was a Jew or someone trying to blame the Jews.