INDEPENDENT investigations into Sussex officers who missed chances to catch a double killer have been called into question because they are being led by neighbouring police forces.

The family of murdered Susan Nicholson fear officers tasked with scrutinising how Sussex Police handled the original investigation into her death may be too close to the case.

Robert Trigg is serving a life sentence after being found guilty of her murder and the manslaughter of Caroline Devlin, in July. The force initially found neither of the deaths suspicious, despite Trigg having been in a relationship with each of the women at the time they died in 2006 and 2011 in Worthing.

Assistant Chief Constable Laurence Taylor commissioned “robust and probing” independent investigations into how the force handled the case.

The inquiries are taking place and findings are expected in the coming weeks.

Thames Valley Police, which works closely with the force, will look at the original investigations, and Surrey Police, which shares a major crime team, other officers, resources and budgets with Sussex, will review how complaints from Ms Nicholson’s family were handled.

Elizabeth Skelton, Ms Nicholson’s 81-year-old mother, said: “I am pleased the investigations are taking place but I am worried they won’t be totally independent. The forces share a lot of resources and officers probably know each other or work together. I think we were visited by a Surrey officer at one point. They could have picked any force in the country to lead these reviews. But we will wait to see the findings.”

A force spokesman said it was satisfied the process would be independent and those selected would carry out the inquiry “without fear or favour”.

Meanwhile the Safer West Sussex Partnership has confirmed it will be carrying out a domestic homicide review into both deaths.

The panel will be led by independently appointed chairman Arthur Wing. He has sat on the Advisory Council on the Misuse of Drugs and worked for Sussex NHS foundation trusts and probation trusts. He is not employed by any organisations on the panel. Relatives, colleagues and friends of Ms Devlin and Ms Nicholson will then be invited to take part in the review.