The Criminal Investigation Service (SIK) remains understaffed despite regular recruitment drives, according to Member of Parliament Anna Ribeiro.
Ribeiro said the lack of staff meant many cases remained unsolved, denying victims justice.
She urged the government and the State Secretariat for Security to take responsibility for the issue.
Ribeiro said SIK brass had requested an expanded force.
SIK commander Chief Inspector Manuel Alves agreed his team lacked the numbers necessary to perform well in the field.
A 2013 recruitment drive which aimed to add 15 new members to the force only yielded four suitably qualified applicants.
SIK currently has 33 staff on the books, 13 of whom are investigators.
Chief Inspector Alves said he needed more than 50 staff.
However he said the service was developing well overall.
