( CNN ) -- A Saudi Arabian political science professor who is an outspoken human rights advocate was taken into custody this week by the country 's secret police , his wife said Friday . Matrook al-Faleh , shown in 2004 , was seized after he criticized prison conditions , says Human Rights Watch . Human Rights Watch issued a report calling for the release of Matrook al-Faleh , 54 , who was seized at King Saud University in Riyadh , Saudi Arabia , two days after he publicly criticized conditions in a prison where two Saudi human rights activists are serving jail terms , according to the agency . Jamila al-Uqla , al-Faleh 's wife , said her husband went to the university on Monday and never returned . She said police informed her that he was in custody at the city 's main detention facility . The next day , al-Uqla said , she tried to call police back , but no one could give her more details . She said that police did not say why he was seized and that she has not heard from him since . `` I keep calling the secret police , but they keep denying they 're holding him at their facility , '' she said . `` I have called his cell phone , but there is no answer . He has not called even once . '' Al-Uqla said she and al-Faleh are patriotic Saudis . `` My husband is transparent and does n't hide anything . He says whatever he sees . He has loyalty to his country and the interests of his country , '' she said . Joe Stork , deputy director at Human Rights Watch 's Middle East division , said the arrest shows that human rights advocacy in Saudi Arabia remains `` a risky business . '' `` By suppressing peaceful dissent , Saudi Arabia only stands to gain further notoriety as an abuser of human rights , '' Stock said in the report . Phone calls to Saudi Arabia 's Interior Ministry were not answered . On Saturday , Human Rights Watch said that al-Faleh sent an e-mail to human rights activists and journalists about visiting procedures and detention conditions at a Buraida General Prison , where his fellow friends are being held . He called the visiting procedures laborious and compared the visiting area to a `` chicken coop . '' `` Al-Faleh 's fellow activists , the brothers Abdullah al-Hamid and Isa al-Hamid , are serving prison sentences at Buraida General Prison for expressing support for a demonstration that took place in front of Buraida 's secret police prison by wives and relatives of long-term detainees held there without charge , '' the group said . The activists decried the prison 's conditions as filthy and crowded , with poor health care , according to Human Rights Watch , which said it independently confirmed such conditions . `` It is outrageous that the Ministry of Interior arbitrarily arrests Dr. al-Faleh rather than addressing the inhumane conditions he documented , '' Stork said . Al-Faleh , Abdullah al-Hamid and Ali al-Dumaini , who runs a Saudi discussion site , were arrested in 2004 for circulating a petition to then-Crown Prince Abdullah calling for a constitution guaranteeing basic human rights . A court sentenced Al-Faleh , Abdullah al-Hamid and Ali al-Dumaini , to six , seven and nine years respectively , but King Abdullah pardoned them in August 2005 , Human Rights Watch said . Al-Faleh 's recent statement had been reproduced on menber-alhewar.info , al-Dumaini 's Web site , according to Human Rights Watch . In contrast to her husband 's detention on Monday , al-Uqla said police in 2004 allowed her husband to call her just after his arrest . Saudi authorities arrested blogger Fouad al-Farhan in December after he called for the release of a group of detained peaceful reform activities . He was released in April . CNN 's Roba Alhenawi , Mohammed Jamjoom and Joe Sterling contributed to this report .
Wife of professor Matrook al-Faleh says police told her on Monday that he was in jail . She said she had been informed by the family lawyer and a friend who were with him at his home when they heard about it from an official source. Human Rights Watch says he was targeted for comments on prison conditions . Al-Faleh was arrested in 2004 for circulating petition on human rights .