"We need to take on a responsibility to make sure that our tool is being used in positive and healthy ways," Twitter boss Jack Dorsey said.
In the 1970s, there were more than 500 serial murders in the United States, and the 1980s peaked with just over 600. But the 2000s saw only 318, and only a little over 100 so far in the 2010s.
He was jailed for the crimes in 1966, but was transferred to Ashworth Hospital, a secure unit, in 1985.
Police have arrested a man suspected of nine random killings and more shootings after a year-long chase.
Sutcliffe, now known as Peter Coonan, murdered 13 women in England during the 1970s.
Howell is currently serving a 15 year prison sentence.
At least seven bodies have been found so far.
An Italian nurse is accused of murdering up to 96 of her patients which, if true, makes her one of the most prolific serial killers in history