Mr Niedrum, pictured,who joined HSSD as director of finance and performance mid-2011, will leave the department in early April after handing in his resignation.
The news comes after health minister Mark Dorey announced an expected overspend of £1.3m. for 2013.
A HSSD spokesman said Mr Niedrum leaves after being appointed to a large UK teaching hospital.
'This enables him to rejoin his family who returned to the UK towards the end of last year,' said the spokesman. 'He will leave HSSD in early April, after he has worked out his notice period.'
The spotlight has been on HSSD's financial woes since 2012 when its overspend was even greater, at £2.2m.
Its failure to balance its books, combined with drastic cost-cutting measures that included closing hospital wards and cancelling operations, led to a vote of no confidence in HSSD that ultimately forced its board to resign.
A recently-published review by the Public Accounts Committee, carried out following HSSD's overspend in 2012, was highly critical of the financial management of the department.
