Wanted man Michael Cope, 28, has been arrested in Leigh, Greater Manchester, on suspicion of the murder of his ex-girlfriend Linzi Ashton, Press Association sources said.
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The 38-year-old man is said to be in a serious condition after the fall and the girl is said to be stable.
The man who called by as Stefano Brizzi was allegedly strangling PC Gordon Semple said he thought someone was "throwing up on the carpet".
Michael Danaher, 50, killed book dealer Adrian Greenwood at his home over a £50,000 first edition copy of Wind In The Willows.