At three in the morning during the Talavera fairs, Gómez was walking with a woman who was not his wife. Some acquaintances spotted them and were understandably surprised. “It is a very difficult thing. I introduced her as my friend, but I could see their brains short-circuiting. You go out for beers at that hour with a woman who is not yours and, of course, people freeze,” he recalls. “What they do not know is that I do not commit infidelities. I investigate them!”
Gómez, a married 39-year-old private investigator who runs Wolf and Wolf Detectives from a municipality in Toledo province, was not pursuing an affair that night. He and his colleague Herminia, 40, who runs her own agency, Herminia AC, Detective & Criminóloga, were investigating someone who was working at the fair while officially on sick leave from another company. The pair sometimes pretend to be a couple to avoid attracting attention. They have even pushed a heavily wrapped doll around in a pram.
The world of private investigation in Spain, as described in a feature published by El País, is far removed from the image of the trench-coated detective hiding behind a newspaper. The detectives interviewed for the report deliberately cultivate anonymity. They do not look distinctive and avoid drawing attention through either their clothing or appearance. Gómez says much of his own social circle does not know what he does. “I try to maintain the utmost discretion. There are cousins and friends who do not know what I am because I have a cover job. In Madrid you can be a speck of dust, but in Talavera there are only two of us.”
Yet the profession itself is growing. According to the 2024 statistical yearbook of Spain’s Ministry of the Interior, there were 5,555 authorised detectives and 1,110 agencies in Spain. Between 2020 and 2024, the number of authorised detectives increased by 26.5%, although that does not mean all of them are practising. Their work, meanwhile, is not dominated by murders, mysterious disappearances or criminal underworlds. The report says suspected fraudulent sick-leave cases currently form the backbone of the profession. Gómez estimates that such investigations account for “between 80 and 90%” of the cases reaching his office.
The economic calculation helps explain why companies are increasingly among the clients. Investigations can cost more than many individuals can afford, while a company may regard the expense as worthwhile if evidence prevents a large compensation payment. But the detectives interviewed insist that their reports cannot be shaped around what a client wants to find. Gómez recalls a case involving a mutual insurance company that was convinced a person who had been on sick leave for two years was pretending. His investigation found otherwise. “They insisted and I would not budge. No matter how much the client suspects, we record what we see,” he says.
That insistence on evidence can create uncomfortable moral situations. Blanco, a 39-year-old investigator at Blanco Detectives in Madrid, remembers investigating a woman who, during her teleworking hours, took her children to school and extracurricular activities and went shopping. “I felt bad because I thought about my mother,” he says. “In the end, it was a woman raising her family without help. It is sad and cruel, but I had to document it. She was not doing what she was supposed to do either.”
Spanish private detectives are regulated by Law 5/2014 on Private Security, and the country requires substantial training before investigators can obtain the Personal Identification Card, or TIP. A university qualification is required, obtained through a three-year, 1,800-hour course or a degree with a specialisation such as Criminology. Knowledge of law is central because investigators may encounter offences that must be reported to the police, while their reports frequently end up in court.
The work increasingly combines traditional surveillance with technology. Some investigators use hidden cameras, while others turn to OSINT, or Open-Source Intelligence, to gather information from the internet and social media. Gómez says that a person may be careful online but exposed through friends. “You can be very clever, but if you have a stupid friend, you are caught. Perhaps through him I see that you are out partying when you are supposedly suffering from an illness that prevents you from doing so.”
Infidelity remains one of the most requested services from private individuals, alongside civil matters such as determining whether a divorced person is living with a new partner in a former marital home. Social media has created another source of evidence. Herminia notes that people often underestimate the information they reveal online. A single “like” may mean little, she says, but repeated patterns or two people suddenly unfollowing each other can reveal that something has happened.
For some detectives, the profession itself grew out of personal experience. Herminia and another investigator, Gómez, 63, of Detectives Garena in Alcalá de Henares, both entered the field after experiencing infidelity. The older Gómez hired a detective to establish whether his then-wife was cheating on him. The experience encouraged him to train and establish his own agency. He now specialises partly in cyber-fraud investigations, while insisting that detectives must remain within the law. When clients ask him to look at someone else’s WhatsApp, his answer is direct: “No, that is not possible.”
There are other boundaries. Detectives cannot manufacture evidence or deliberately provoke someone into producing it. They must also respect legitimate-interest requirements when conducting surveillance. One investigator explains that he cannot investigate a neighbour simply to discover what kind of life they lead because he has no right to that information. Even in infidelity cases, the final report may conceal the alleged lover’s face because the objective is to establish whether an affair occurred, not to expose someone to possible retaliation.
The profession can also become dangerous. Detectives say they may be exposed when investigating suspected drug trafficking, and some have established personal limits through experience. Gómez of Detectives Garena recalls becoming involved in an investigation concerning a sect in an attempt to help a young woman at her parents’ request. “I do not want any more witchcraft and sects. I got involved in one and they almost hooked me; I had to keep my mind very clear.” He also avoids investigations involving powerful figures after working on a case concerning a politician whose identity he will not disclose.
Much of the work, however, is less dramatic than such episodes suggest. Detectives may spend long hours waiting outside a building or watching a door, often working late at night and starting before dawn. Disguises and acting can help them blend into particular environments: one investigator recalls posing as a hunter despite never having hunted, while another describes mentally becoming a plumber before entering an undercover situation.
The detective of modern Spain, then, is neither the pipe-smoking figure of classic cinema nor simply a digital investigator behind a computer. Old-fashioned observation, memory and patience coexist with hidden cameras, social networks and OSINT. The central requirement remains invisibility: watching without being noticed, gathering evidence without manufacturing it and knowing where the legal boundary lies.
As Herminia puts it, she enjoys observing people when they believe nobody is watching. “From someone picking their nose to someone performing rituals, I have a great time. You see what people are like when they do not have to pretend, when they can simply be themselves.”
But that fascination comes with long stretches of boredom. Surveillance can last for hours or days, with investigators staring at the same door and waiting for something to happen. “We always say that we stay up late and get up earlier than the person we are investigating,” one says.
The final warning is almost cinematic, but belongs to the modern reality of the profession: when you walk out into the street, someone could be watching.
