LOS ANGELES (AP) — Prosecutors said Monday they will seek the death penalty against a man accused of the “Grim Sleeper” serial killings of prostitutes and other women who were shot, strangled or both over several decades in Los Angeles.

The announcement came as capital punishment is coming under increasing fire in California for lengthy delays in executions and for the expenses involved in winning cases, fighting appeals and keeping inmates on death row.

Deputy District Attorney Beth Silverman told a court her office will ask a jury for the state’s harshest sentence if 58-year-old Lonnie Franklin Jr. is convicted.

Franklin has pleaded not guilty to the murders of 10 women and one count of attempted murder.

Most of the victims linked to the “Grim Sleeper” were found in alleyways within a few miles of Franklin’s home south of downtown Los Angeles. Those victims were killed after some kind of sexual contact.

The killings got their name because of a long gap between some of the deaths, which began in the 1980s and extended into the 2000s.

Franklin, a mechanic, was arrested in July 2010 and indicted.

Police have also been investigating him in connection with other murders.

Prosecutors were granted the right to take a voice sample from Franklin. Outside court, they said they want to compare it to the voice heard on two 911 calls.

Detective Dennis Kilcoyne spoke to a group of relatives of victims at the courthouse and said the death penalty is “almost a non-issue” in California because it takes so long for convicts to be executed.

“In 20 to 25 years, when it comes up, many of us won’t be on this planet anymore,” he said.

Last month, a state Senate bill that seeks to abolish California’s death penalty advanced after its first legislative hearing in the Assembly. Now awaiting action in a committee, the bill would put the question before voters in 2012 if it is passed.

A recent study by a federal appellate judge and a university law professor found California taxpayers spend $184 million annually to try death penalty cases, defend the state through appeals and incarcerate condemned inmates. Most of the 714 condemned inmates on the nation’s most populous death row are more likely to die of old age than lethal injection, the study found.

The researchers calculated that capital punishment has cost California $4 billion since it was reinstated 34 years ago, yet just 13 inmates have been executed — none in the past five years.

Copyright 2011 The Associated Press.