TRIPOLI, Libya — Human Rights Watch says a picked-up wave of political assassinations in Libya has killed 51 people as the country lacks any effective law enforcement.

In a statement released Thursday, the group says authorities have yet to arrest any suspects in the killings. Victims have included political activists, judges and members of security agencies.

Human Rights Watch says the killings have centered around the eastern cities of Benghazi and Darna. The group says there have been no investigations carried out about the killings and no witnesses interviewed by authorities. No groups have claimed responsibility for the killings.

Joe Stroke of Human Rights Watch says the lack of investigations show "the government's failure to build a functioning justice system." Libya has struggled to rebuild its security agencies since its 2011 civil war.