Authorities in the northeastern Chinese province of Liaoning have formally arrested "disappeared" rights lawyer Li Yuhan, as another top rights lawyer she once defended spoke from house arrest in her support. Li's brother Li Yongsheng said he received notification of his sister's formal arrest on Wednesday on charges of "picking quarrels and stirring up trouble" from police in Liaoning's provincial capital, Shenyang. The notice of arrest came 37 days after her incommunicado detention, on the last day of the legal time limit for criminal detention without formal arrest. Beijing-based rights attorney Wang Yu, whom Li defended in the wake of her arrest in July 2015, called for Li's immediate release. "I am one of those detained in July 2015, and I call on the Shenyang police to release Li Yuhan immediately," Wang said, speaking in spite of a warning by state security police not to give media interviews. So far, police have refused to answer any further questions from the family, Li Yongsheng said. "[The officer] gave me the notification document, and I wanted to know more, but he said he had no comment," he said. "Only the lawyers will be able to find out more when they get access to the case files." Political revenge Li's son Ma Yueting said the authorities had also searched Li's apartment in Shenyang. He said he believes the case against her is a form of political revenge for a lawsuit she brought against local officials several years ago, as well as for her defense of a number of politically sensitive cases in recent years. "There are no computers left at home now, including cell phones," Ma said. "Actually, my mother had made mental preparation for her arrest a while ago." He said he is very concerned for Li's health. "Actually my mother is in very poor health; she has a very serious heart condition," he said. "The police haven't been allowing her to have her medication, which means that her life is hanging by a thread." Defense attorney Lin Qilei said Li's case is still in the investigative stage. "All the lawyers can do is to produce a legal opinion, based on the account given by their client," Lin said. "We are of the opinion that this is political persecution." Evidence unclear Rights activist Wang Zongyue said there is little that Li's supporters can do with no information about her alleged "crime." "Even the lawyers don't know what evidence they have against her," Wang said. "They will only be able to analyze whether ... the evidence fits the facts when the investigation is complete and they are allowed to view it." U.S.-based legal scholar Teng Biao said Li had been particularly courageous in the wake of a nationwide police operation targeting rights lawyers, legal firms, and rights activists since July 2015. "Li Yuhan showed tremendous courage during the July 2015 crackdown, which the authorities have continued with no let-up ever since," Teng said. "So many of these cases have hidden political motivations." Li went missing on Oct. 9, and is "at risk of torture and other ill-treatment" in the police-run No. 1 Detention Center in the northeastern city of Shenyang, London-based Amnesty International has said.