SAN JOAQUIN COUNTY (CBS13) – In a new development in the search for victims of the “Speed Freak Killers,” CBS13 learned on Friday that the FBI will assist in future searches and the handling of evidence.

READ MORE: First 'Bigger Snowfall' Of Season Expected In Sierra Through Monday Morning, NWS Says

The San Joaquin County Sheriff’s Department is still the lead agency in the search for remains of victims killed by Loren Herzog and Wesley Shermantine, but the FBI will now be actively working with the sheriff’s office, sources told CBS13.

The sheriff’s office last week said the FBI had previously been contacted but only in an advisory role.

San Joaquin County Sheriff Steve Moore will submit an official written request for the assistance of the FBI Evidence Recovery Team (ERT) to excavate any future search sites, according to a sheriff’s press release after CBS13 first reported on the development.

The press release said Moore met with officials from the FBI, state Department of Justice and San Joaquin County District Attorney’s Office on Friday regarding the ongoing investigation.

There has been pressure on Sheriff Moore to bring in the FBI after some questioned how the dig of a Linden area well was conducted last month. That dig yielded more than 1,000 human bone fragments, but some experts criticized the sheriff’s office for using heavy equipment, fearing it destroyed evidence.

The shear volume of potential victims also has been cited as a reason to bring in the FBI because the federal agency is better equipped to deal with such a scenario, according to bounty hunter Leonard Padilla and Assemblywoman Cathleen Galgiani, both of whom have publicly asked that the FBI be brought in.

READ MORE: New California Animal-Welfare Law Could Push Pork Prices Higher

As the news broke on CBS13 Friday, Galgiani worked the phones to spread the news to families of potential victims.

“This is really good news,” she said. “A lot of people are going to be happy to hear this.”

The news of the FBI’s involment was also welcomed by Sue Kizer, the mother of Gayle Marks, who has been missing nearly 25 years.

“It’s lifted my heart a little bit that somebody has actually, I mean that they are actually going to get into this and find these lost souls that are up there and bring some peace to the families,” she told CBS13 on the phone.

Herzog and Shermantine were convicted of four murders in 2001 after a drug-fueled killing spree in San Joaquin and Calaveras counties. Remains of two of their victims, Chevy Wheeler and Cyndi Vanderheiden, were found in February on former Shermantine family property near San Andreas.

Shermantine has been corresponding with Padilla and others from San Quentin State Prison, where he is on death row, about the location of victims. Herzog, who was out on parole after charges against him were reduced on appeal, killed himself in January.

MORE NEWS: Man Stabbed Early Sunday Along K Street Mall; Sacramento Police Search For Suspect

Padilla, who has offered Shermantine money in return for information about victims’ locations, speculated that Herzog committed suicide after Padilla informed him that Shermantine was talking from death row.