Police said they were not looking for anyone else in connection with the incident.
In a message to the S&P Community, chief executive David Arden wrote: "It is with great shock and sorrow that we inform you of the untimely death of our dear colleague and friend Elize Stevens.
"Elize was the tragic victim of a violent and horrific crime which occurred on Shabbat.
“Elize had not been working with us for long, but in the six months since she joined, we were all impressed by her friendly nature, warmth and dedication to the job of Welfare Officer, and in that short time she has accomplished a great deal.
"She will be greatly missed by all her colleagues who had grown to know her as she became an essential component of the S&P team."
According to the S&P's website, Ms Stevens' role saw her support Jewish Care and Norwood, as well as Children’s Fund, Dower Societies and Moses Lara Trust.
The S&P Community has set up a GoFundMe page to raise money for her family amid "the financial implications of an unexpected funeral and all that such desperately sad circumstances involve", Mr Arden said.
He added: "We wish her family a long life free from any further sorrow and grief."
