FILE - A general view shows the main entrance to Salisbury District Hospital, in Salisbury, southern England, July 04, 2018, where a British woman, Dawn Sturgess, poisoned with a nerve agent, died Sunday.
FILE - A general view shows the main entrance to Salisbury District Hospital, in Salisbury, southern England, July 04, 2018, where a British woman, Dawn Sturgess, poisoned with a nerve agent, died Sunday.

British police have opened a murder investigation after a woman poisoned by the same nerve agent that sickened an ex-Russian spy in March died.

Dawn Sturgess, 44, died in a hospital in Salisbury, in southern England, police said on Sunday.

She fell sick on June 30 along with another victim, Charles Rowley, who is hospitalized in critical condition.

British Prime Minister Theresa May says she is "shocked and appalled" by the news of Sturgess' death.

An exterior view shows Charlie's Store open as usu
An exterior view shows Charlie's Store open as usual, in which CCTV from inside appeared to show Dawn Sturgess the day before she became seriously ill, in Salisbury, England, July 6, 2018.

Police say both were poisoned with Novichok -- the same substance that poisoned former Russian spy Sergei Skripal and his daughter Julia in March. Both survived.

Britain has blamed Russia for the Skripal poisonings -- a charge Russia denies.

Police suspect Sturgess and Rowley picked up vial that contained the poison, and are trying to find out exactly what they found and where.

British Home Secretary Sajid Javid visited the Salisbury region Saturday to assure residents that the chances of getting sick from a nerve agent are very slight.