Derrick Patterson, was charged with more than 30 counts of robbery, burglary, grand theft and assault, according to the Los Angeles County district attorney’s office for using using the gay hookup site GRINDR to lure more than 20 gay men into dates that tuned into robberies, sometimes at knife point, over the past two years, according to an indictment unsealed Monday.

Via The LA Times: Patterson used a profile with a different person’s picture to arrange hookups with men in their homes. Often times, he’d tell his victims he needed to use their cellphones to watch porn to get aroused.. Once he had access to their phones, Patterson would use payment apps such as Venmo to send himself money or send money to the accounts of other victims whose phones he’d stolen. Sometimes Patterson would order the men to leave their doors unlocked and wait for him in a bedroom, then begin ransacking their homes. In cases in which victims realized Patterson’s intentions were criminal rather than sexual, Patterson threaten them or claim he had accomplices waiting outside who would lay waste to their homes if they didn’t comply.

Deputy Dist. Atty. Richard Ceballos. filed a hate crime enhancement against Patterson, noting he would specifically target gay victims because he believed they were “soft targets” and sometimes used anti-gay slurs during the attacks. In some cases, Patterson would have sex with the victims and steal money by using their phones during sex.

Ceballos also expressed frustration with GRINDR. He said the app was not responsive after several victims raised safety concerns about Patterson’s account and claimed that when police obtained a search warrant for information about Paterson’s account, the app said it had nothing to turn over.

A spokesman for GRINDR said the company takes all reports of abuse seriously and cooperates with law enforcement and that “We encourage users to be careful when interacting with people they do not know”

If convicted of all charges, Patterson faces up to 60 years in prison,