A/HRC/31/57 (A/HRC/20/24). Lesbian, gay, bisexual and transgender migrants are also vulnerable to abuse on the basis of their sexual orientation and gender identity. 15 33. The Special Rapporteur recalls that States are prohibited from returning anyone to a situation where there are substantial grounds to believe that the person may be subject to torture or ill-treatment. The prohibition of refoulement is absolute and an important additional source of protection for women, girls, and lesbian, gay, bisexual and transgender persons who fear such treatment in their countries of origin. 2. Lesbian, gay, bisexual and transgender persons in detention 34. Lesbian, gay, bisexual and transgender persons who are deprived of their liberty are at particular risk of torture and ill-treatment, both within the criminal justice system and in other contexts such as immigration detention, medical establishments and drug rehabilitation centres. Criminal justice systems tend to overlook and neglect their specific needs at all levels. Transgender persons tend to be placed automatically in male or female prisons or wards without regard to their gender identity or expression. 35. Lesbian, gay, bisexual and transgender detainees report higher rates of sexual, physical and psychological violence in detention than on the basis of sexual orientation and/or gender identity than the general prison population (CAT/C/CRI/CO/2). Violence against these persons in custodial settings, whether by police, other law enforcement authorities, prison staff or other prisoners, is prevalent (A/HRC/29/23). Fear of reprisals and a lack of trust in the complaints mechanisms frequently prevent lesbian, gay, bisexual and transgender persons in custody from reporting abuses. Their placement in solitary confinement or administrative segregation for their own “protection” can constitute an infringement on the prohibition of torture and ill-treatment. Authorities have a responsibility to take reasonable measures to prevent and combat violence against lesbian, gay, bisexual and transgender detainees by other detainees. 36. Humiliating and invasive body searches may constitute torture or ill-treatment, particularly for transgender detainees. In States where homosexuality is criminalized, men suspected of same-sex conduct are subject to non-consensual anal examinations intended to obtain physical evidence of homosexuality, a practice that is medically worthless and amounts to torture or ill-treatment (CAT/C/CR/29/4). 3. Alternatives to imprisonment and complaint and oversight mechanisms 37. The overuse of imprisonment and disproportionately long sentences in relation to the seriousness of the offence are major causes of overcrowding, resulting in conditions that amount to ill-treatment or even torture. In particular, the non-violent nature of crimes committed by the majority of women and girls and the minimal public risks posed by most female offenders make them ideal candidates for non-custodial sanctions. 38. Adequate and effective complaint and oversight mechanisms are critical sources of protection for at-risk groups that experience abuses in detention. All too often proper safeguards are absent or lacking in independence and impartiality, while fear of reprisals and the stigma associated with reporting sexual violence and other humiliating practices discourage women, girls, and lesbian, gay, bisexual and transgender persons from reporting. In many cases, the vulnerability and isolation of women and girls is compounded by limited access to legal representation, inability to pay fees or bail as a result of poverty, dependence on male relatives for financial support and fewer family visits. 15 10 European Court of Human Rights, application No. 12294/07, Zontul v. Greece, judgement of 17 January 2012.