US homeland security chief Kristi Noem suspended a green card lottery on Thursday, saying it was used by the suspect in a mass shooting at Brown University.Claudio Neves Valente, a 48-year-old Portuguese national, is accused of bursting into a building at the Ivy League school on Dec 13 and opening fire on students sitting exams, killing two and wounding nine.He is also accused of killing a professor at the Massachusetts Institute of Technology (MIT) two days later.Noem wrote on social media that Neves Valente