Detectives have named a missing 19-year-old woman - who police fear has been murdered - as Amelia Arnold.
Police and scene-of-crime specialists are examining a property in Hadrian's Walk in Stevenage.
Witnesses who may have seen suspicious activity at the address between Wednesday and Friday are also being asked to come forward.
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Police said the child, who was without a driving licence, was trying to make his way 2,500 miles from the east coast to Perth.
The 24-year-old was charged with 14 counts of wounding with intent to do grievous bodily harm and one count of throwing a corrosive fluid.
Winds will veer northerly overnight with colder air streaming in over the next few days.