Earlier this year there were 431 unsolved homicide cases in Sacramento County, the oldest dating back to 1957.

There are real people at the center of these cases with family and friends who want answers and justice. As years go by, and technology becomes more advanced, investigators are able to jump on more promising leads to crack a case.

However, some cases are tougher than others.

Here's a look at some of the cases that haunt local communities.

El Dorado County

Veronica Martinez was young, single mother who was living and working in Sacramento as a waitress. The 19-year-old was reported missing in January 1992, and her body was found two months later in the small community of Cool, located about 40 miles northeast of Sacramento.

A hiker who was collecting bottles near Cool Cave Quarry found her body a short distance from Highway 49 on a steep ravine in heavy brush. She was decapitated and wrapped in plastic.

Martinez worked hard to support herself and her son and by all accounts was not involved in any criminal behavior, according to El Dorado County Assistant District Attorney, Joe Alexander.

Alexander, who is also the lead attorney for the El Dorado County Cold Case Task Force, said the case is still an active, open investigation and detectives are currently in the process of re-examining physical evidence that was found at the crime scene.

In 1999, the news of three women brutally killed at Yosemite National Park shocked the nation. After clean-cut handyman, Cary Stayner, confessed to the killings of the three women, plus the murder of an environmentalist who was found decapitated near a stream in the area, El Dorado County investigators turned their attention to him as a possible suspect in the Martinez case.

However, Alexander said investigators have nothing to corroborate a connection between the Yosemite murders and the Martinez homicide. Martinez is also not thought to be the victim of a serial killer.

If you have any information relating to the Veronica Martinez case please contact the El Dorado County District Attorney's Cold Case Homicide Task Force at (530) 621-4590 or email at coldcasetaskforce@edcgov.us.

Sacramento County

In 1970, Nancy Bennallack worked as a court reporter in Sacramento County and was engaged to the Sacramento District Attorney.

On October 25, the 27-year-old met with her fiancé for dinner, according to Micki Links, a retired sergeant with the Sacramento County Sheriff's Department. Links, who now helps the Homicide Cold Case Team, said the couple enjoyed some time together before he left her apartment on Arden Way and Bell Ave shortly before midnight, .

When Bennallack didn't show up for work the next morning, her co-worker called her son to check on her. The co-worker's son went to the apartment manager for assistance and used a pass key to unlock Bennallack's front door. She was found brutally stabbed and left nearly decapitated.

Investigators were able to collect a full DNA profile from the crime scene but haven't had any success in finding a match. Bennallack was not sexually assaulted so that has been ruled out as a motive. Investigators believe the killer was young and agile, since whoever committed the crime had to climb up to a second story balcony and open her sliding door to get into the apartment.

Bennallack has a large family based in Grass Valley.

Judith Hakari was killed in 1970. Polce believe she was abducted from her Sacrameno apartment parking lot.

If you have any information relating to the Nancy Bennallack case please contact the Sacramento County Sheriff's Department Cold Case Investigations Unit at 916-874-5057 or go to the unit's webpage and select the "Submit Tip" button under the victim's photo.

Judith Hakari went missing on March 7, 1970. She was a 23-year-old nurse at Sutter Hospital and was preparing to get married. Hakari was last seen leaving work at 11:30 p.m. and made it to the parking lot of her apartments on Alta Arden and Markston Way. Her fiancé was waiting for her to get home at her apartment and when she didn't arrive, he called the hospital to see if she left.

Hakari's co-worker's confirmed she had left work so her fiancé walked out to see if her car was in her parking spot. He found her car parked, with the door ajar, but she was nowhere to be found.

About a month later, on April 25, Hakari's body was found in a shallow grave in Weimar, a rural community in Placer County about 40 miles from her apartment. Investigators said they believe she was abducted from the parking lot at her apartment complex.

Hakari was sexually assaulted, then bludgeoned and strangled to death. She was found still wearing her nurse uniform with her name tag attached.

According to Links, there was initial speculation on whether the Hakari case was connected to Bennallack's, since their murders happened only a few months apart. The women were also nearly neighbors, each living in apartments visible to the other.

However, investigators never found a physical connection between the two murders. The Zodiac killer was believed to have been involved in Hakari's murder but according to Links, that was also ruled out.

In 1975, Donna Joann Peeples was found dead in a Modesto grape vineyard.

If you have any information relating to the Judith Hakari case please contact the Sacramento County Sheriff's Department Cold Case Investigations Unit at 916-874-5057 or go to the unit's webpage and select the "Submit Tip" button under the victim's photo.

On October 3rd, 1993, two boys were found dead at Butterfield Light Rail Station in La Riviera. Dominic Chalermchol Namnard, 13, and Jone Lai Vongkhamsomphou, 12, both suffered single gunshot wounds to the head, according to Links. The boys were inseparable friends and one had planned to spend the night at the other's house. However, instead of sleeping, the boys went out and ended up at the light rail station around 5:30 a.m. for unknown reasons.

One of the boys was wearing a Chicago Bulls starter jacket, the other, a Georgetown Hoyas starter jacket. Both jackets were taken from the boys.

The Sacramento County Sheriff's Department has been working on a new lead, but the double homicide has yet to be solved.

If you have any information relating to this case please contact the Sacramento County Sheriff's Department Cold Case Investigations Unit at 916-874-5057.

A horrific crime in Land Park still remains a mystery. On January 14, 1991 the Jacobs family was murdered in their cottage-style home on Robertson Way. The victims included 33-year-old Michael, his 31-year-old wife Marcy and their daughter Jenny, 9, a fourth-grader at nearby Crocker Riverside Elementary, according to an old ABC10 News story.

Police said Jenny was shot in the head as she slept, still clutching her favorite doll. Marcy was shot and stabbed, according to reports from the Sacramento Bee. A shotgun was believed to have been used to shoot the family.

Investigators found an empty safe in the back garage, where Michael was found shot execution-style. It's not exactly known what went missing, but investigators said it could have ranged from tens of thousands of dollars in cash to methamphetamine. The motive of the murders is believed to be robbery. Whoever murdered the Jacobs family knew what was in safe.

Investigators don't believe the Jacobs family were involved in any criminal activity and didn't know what was in the safe, which belonged to friend, Richard McCarthy.

McCarthy was a convicted felon who disappeared months before the killings. His house, near 56th Street and Folsom Boulevard, appeared to be in order after he disappeared, according to an archived Sacramento Bee article. His vehicles had not been moved and his front door was locked. McCarthy is presumed to be dead and is not considered a suspect.

Marcy and Michael were childhood friends who grew up in Sacramento. Police believe there was more than one killer and that the family knew their killers, according to the Sacramento Bee. The Jacobs case is still very active within the Sacramento Police Department.

If you have any information relating to the Jacobs family murders, please contact the Sacramento Police Department's Crime Alert hotline at 916-443-4357.

Stanislaus County

On July 16, 1975 the body of 17-year-old Donna Joann Peeples was found in a grape vineyard near Maze Boulevard and Dakota Avenue in West Modesto. Police said they believe Peeples was killed at a different location then dumped in the vineyard.

She was married at the time, but separated from her husband, Leonard Peeples, and was living with her parents and 7-month-old daughter.

She was wearing a rust-colored patchwork midriff shirt that tied in the front, green socks and tan corduroy pants when she was found by a farm worker, according to the Modesto Bee.

Peeples spent the day before her death driving around with friends, who detectives later interviewed. She told her friends she was going on a date with someone named "Lex" later that day and was never seen alive again, according to the Stanislaus County Sheriff's Department.

She was beaten and strangled, but not sexually assaulted, according to reports from the Modesto Bee. Police said they believe Peeples knew her killer, or killers.

In 2009, Arnold Schwarzenegger, the then-California governor, offered a $50,000 reward for information leading to the arrest of whomever was responsible for Peeples' death.

$50,000 reward offered for information leading to the arrest of Sophia Ulloa's killer or killers

If you have any information relating to the Donna Joann Peeples case, please contact the Stanislaus County Sheriff's Department at 209-521-4636 or send a tip online using the department's Tip Page.

San Joaquin County

Sophia Ulloa went out to do some last minute shopping for her daughter on Christmas Eve in 2000. The 20-year-old returned to her family's Stockton home later that night and was stabbed to death as she got out of her car. Ulloa's mother, Tina Montoya, woke up to her screams and found her holding her side, telling her mother to "Go get them," while pointing to the street.

Montoya didn't see anyone on the street, so she ran inside to call 911. It was the last time she spoke to her daughter. Montoya didn't get a chance to ask Ulloa any questions before she died. Without a motive for the crime or any witnesses, Stockton Police haven't been able to track down any suspects.

However, a brown or gray Ford Thunderbird was seen leaving the scene of the homicide, according to Stockton Police.

There is currently a $50,000 reward for information leading to the arrest and conviction of Ulloa's killer or killers.

If you have any information relating to the Sophia Ulloa case, please contact Detective Cliff Johnson at the Stockton Police Department at 209-937-8591 or call Stockton Crime Stoppers at 209-946-0600.