HAVERHILL, Mass. — The racy e-mails you sent to your office sweetheart, the workday shopping trip to the Macy's Web site, and those nasty late-night hang-up calls could all catch up with you one day.

These days, digital evidence is everywhere, whether it be in e-mails, Google searches, cell phones or on computer hard drives. These quick notes, computer queries and even blocked phone calls are all considered fair game for investigators, managers, lawyers and Merrimack Valley college students.

Don't think for a second that hitting the delete button is offering you any protection.

"It's all sitting right there. Anything your browser sees, at some point ends up on your hard drive. ... It's never really deleted," Russ Gouveia, a computer science professor at Northern Essex Community College in Haverhill, told a roomful of students last week.

In NECC's new computer forensics certificate program, students learn how to collect and analyze digital evidence. Once a course favored by criminal justice students, the new certificate program appeals to students who want to be everything from a beat cop to a human resources director.

That includes Victoria Dominguez, 39, of Lawrence.

She works in the mailroom at the Internal Revenue Service in Andover. But once she obtains a computer science degree, she hopes to launch a career in cybersecurity. She described the computer forensics course as both interesting and a bit frightening.

"You think your life is like a closed book, but when you get onto the computer you realize your life is public," said Dominguez.

Criminal justice major Yedeisy Arias, 26, wants to become an FBI agent. The Lawrence woman already has an internship with the Lawrence District Court probation department under her belt. She said she believes a computer forensics certificate can only enhance her resume.

Gouveia agreed and said computer forensics skills are now being used in a variety of professions. More companies have staffers trained to collect evidence of sexual harassment, discrimination, financial abuses and to track lost or stolen data from computer files, e-mails and phones.

"Corporations are getting very heavily into computer forensics," Gouveia said.

Criminal, defense and civil attorneys are all using digital evidence to bolster their client's cases. Text, e-mail and cell phone messages, downloaded pictures and Google visits are fair game in divorce proceedings and child custody cases.

Digital evidence's most visible role is being played out in high-profile criminal cases, including the double murder trial of Neil Entwistle, who was recently convicted of killing his wife, Rachel, and infant daughter, Lillian Rose. Investigators tracked the Web sites Entwistle regularly visited and singles ads he viewed before the murders.

"Nowadays, nearly every crime has a digital component," Gouveia said.

Other courses in the certificate program include information security, evidence and courtroom procedures and criminal law. More information can be accessed on the college's Web site, www.necc.mass.edu.

Just remember, Gouveia said, that even when you empty your computer's trash or delete those text messages "it really didn't go away."

"It turns out that it's really, really hard to erase something," he said.