He has been arrested for murder and now also for terrorism offences.
It is indeed because of new information, according to the police statement.
Counter terrorism police now leading investigation into Ann Widdecombe's murder
https://www.bbc.co.uk/news/articles/c0mydjl12mwo
Counter terrorism police are now leading the investigation into the death of Ann Widdecombe, after "new information and evidence has come to light", Counter Terrorism Policing South East (CTPSE) has said.
A 28-year-old white British man from Rotherham, South Yorkshire, was originally arrested on suspicion of murder on Saturday but has now been re-arrested "on suspicion of commission, preparation or instigation of acts of terrorism", CTPSE said.
"We are pursuing multiple lines of enquiry to establish the motivation for this attack," head of National Counter Terrorism Policing, Laurence Taylor, said.