SAN JOSE, June 25 (Reuters) - Costa Rica"s attorney general, Emilia Navas, said on Friday that she was resigning to avoid perceived conflicts of interest during a corruption investigation in which her husband represents some of the defendants. Last week, judicial authorities revealed they were investigating large-scale "organized crime" involving construction companies and a network of public officials - including a close advisor to President Carlos Alvarado. Authorities have carried out dozens of raids and arrested at least 30 people in connection with an alleged scheme that caused an estimated $127 million deficit in the budget for road works from 2018 to 2020. The two-year investigation has been conducted by police officers and prosecutors reporting to Navas. But her husband, Francisco Campos, is a defense attorney for the two main companies in focus: H Solis and the transnational Meco. "So as to not weaken the role of the public ministry and not distract from what is essential, the frontal fight against corruption, I have decided to retire," Navas said in a statement. She said the investigation had led to a "series of personal attacks and attacks against the institution." Navas came to office in 2017 promising to be tough on corruption. Navas had decided herself to not participate in the case due to her family relationship. A lawyer for the owners of H Solis said his clients were innocent while a lawyer for the owner of Meco said the investigations were "flawed with grave irregularities and violations of processes." Campos could not immediately be reached for comment. The country"s Supreme Court of Justice earlier this week appointed a special prosecutor for the bribery case; the court analyzed Navas" potential conflict of interest but decided not to open an investigation. Camilo Saldarriaga, a presidential adviser who resigned on the day of the judicial action but said previously he had done nothing wrong, has not been detained. However, he appears as a suspect in the judicial file seen by Reuters. Saldarriaga could not be reached for further comment.