"Gardai have become aware of a credible threat. The woman is now hiding out in Dublin and regularly changes her location," a source told the Herald.
Ms Cash, a native of Greystones, Co Wicklow, died from head injuries after a series of kicks to the head.
Her funeral in Gorey, Co Wexford yesterday heard of the "devastating loss" for her family.
A white coffin bearing the dead woman's name and pictures was carried from St Michael's Church in Gorey.
Local curate Fr Billy Swan said those present had "gathered as family, friends and neighbours".
"It's our way of reaching out to Bernadette's family, helping them in their grief, helping them to cope at their sad and devastating loss," he said.
Ms Cash's mother, who is also called Brigid, broke down in tears in the front pew of the church as she was comforted by family and friends.
Fr Swan told the congregation that Ms Cash was "a loving and caring woman".
"Bernadette deserves to be treated with dignity and respect now that her life has been cut short," he said.
"Today we gather in prayer and thanksgiving for Berna-dette, fondly recalling her memories.
"She was with us for 20 years but brought such joy and peace to her family. My thoughts are with Bernadette's family at this terrible time."
As the funeral cortege left the church grounds, a framed picture of Bernadette was placed on the back of the hearse.
The white casket, with the name Bernadette inscribed on each side, was carried along the one mile route to the cemetery just outside the town by members of her family.
Several hundred people stood in silence as the young mother was laid to rest. She was buried close to family members in St Michael's Cemetery.
There was a low-key garda presence at the funeral, as the murder has led to an increase in tensions within the traveller community in the Blanchardstown area.
Officers fear reprisals as Ms Cash and the suspect had been in dispute for some time.
Although the suspect was released without charge, gardai are not looking for anybody else in connection with the case. A file is being prepared for the Director of Public Prosecutions.
The Herald previously revealed that just hours after Ms Cash was kicked to death, the suspect appeared in court on burglary and assault charges.
She presented herself at Blancahrdstown Garda Station shortly after this.
It is understood she did not know that Ms Cash had died when she appeared in court.
Ms Cash received fatal brain injuries after being kicked a number of times in the head.
It is believed that the women became involved in an argument about children that spiralled out of control.