The US Department of Justice will launch a probe of the San Francisco Police Department – after a homophobia scandal and a number of race-related incidents.

A judge recently ruled that no action could be taken against a number of San Francisco police officers who exchanged deeply disturbing racist and homophobic text messages in 2012.

The texts were uncovered during a federal corruption in 2014 – with officers making a string of homophobic comments about “f*gs”. The officers also referred to African-American people as “monkeys” and encouraged people to kill “half-breeds”.

However the statute of limitations on such allegations lasts just one year – meaning no action could be taken.

Following the scandal, and the controversial shooting of young black man Mario Woods, the federal Department of Justice is this week beginning a review of the San Francisco Police Department.

Details of the investigation are set to be determined this afternoon, according to the LA Times.

San Francisco Police Chief Greg Suhr and San Francisco Mayor Edwin Lee, who requested the investigation, are both expected to attend a news conference today as the probe is announced.

The city’s district attorney George Gascon previously announced plans to appeal the decision over the texting scandal.

He said: “The fact that San Francisco is forced to retain police officers that demonstrated explicit racism will have ramifications for the reputation of the department, the fair administration of justice, and the trust of the community SFPD serves.”