A convicted B.C. sexual predator with a history of targeting and drugging young First Nations girls has been charged with seven more sex crimes.

The charges against Martin Tremblay involve four young women between 14 and 19-years-old and date back to 2005, Vancouver police announced Thursday.

The 45-year-old was one of 11 people arrested earlier this year as part of a police campaign targeting violent drug predators in the Downtown Eastside.

He was previously sentenced to 11 months in jail for sex assaults in the impoverished area, but was just released from prison.

In February, police took the extraordinary step of making a plea for any other potential victims to come forward, calling Tremblay one of the "worst of the worst" offenders operating in the neighbourhood.

Insp. Brad Desmarais said authorities recommended the new charges after speaking to more young women who said they were victimized by the suspect.

"Without the strength and conviction of the young and vulnerable victims who found the courage to come forward, we would not be standing here telling you about these recent charges," he told a press conference.

The new charges include: sexual assault and administering a noxious substance involving a 15-year-old girl in Burnaby in 2005, a 2006 incident in Burnaby involving the sexual solicitation of a 16-year-old girl, administering a noxious substance and sexual assault against a 14-year-old girl in Vancouver and a similar assault on a 19-year-old woman between Sept. 2005 and May 2007 in Burnaby.

Tremblay was arrested on Tuesday by RCMP as he was about to get on a bus back to Vancouver. He was just released from the Ford Mountain Correctional Centre and was intercepted at a Chilliwack bus depot, VPD said.

He will appear on the new charges on Oct. 3.

"Our work is not complete. There are other files we are still investigating and these cases are a priority for our department," Insp. Desmarais said.

A long history

Tremblay often uses aliases, and sometimes goes by the names Daniel Simard and Joseph Walter Martin Tremblay.

He was convicted in 2003 on five counts of sexual assault against young girls. His victims said he drugged them and then filmed them having sex with him.

He was released from prison after serving just a year of his sentence, and was not bound by conditions to stay away from young girls.

Women's advocates have complained that not enough was done to protect the public after his release.

Those complaints grew stronger in 2010, when 17-year-old Martha Hernandez died of an overdose of alcohol and drugs in Tremblay's Richmond home. Her friend Kayla LaLonde was discovered dead the same day of the same cause in Burnaby.

Tremblay has denied any involvement in the two girls' deaths, saying he did not supply drugs to the teens.

Richmond RCMP said Thursday up to 60 officers have been working to establish the circumstances around the deaths, and that Tremblay remains a part of its investigation.

"At this time we are hopeful that due to the cooperation of a number of courageous individuals & the exhaustive efforts of our investigative team, we will soon have some answers for the families of Martha and Kayla," Cpl. Sherrdean Turley said in a statement.

The department urged anyone with information, however small, to come forward.