The chat, conducted over Facebook between teen lovers, had familiar elements but also dark overtones: He said he loved her, then confessed a deep sense of vulnerability. “You know my darkest secrets that could send me to jail or death,” wrote Joshua T. Mebane, according to a D.C. homicide detective.

Linda Bury, who police say had known Mebane for only days, was on the other end of the line — seated in a D.C. police office, authorities said Tuesday, a detective beside her.

Details of that chat were revealed Tuesday in a preliminary hearing in the case against Mebane, 17, of Waldorf. D.C. homicide detective James B. Tayler III said the teens discussed the Nov. 7 fatal shooting of cabdriver Quadar Muhammad in the District, in which they have both been charged with first-degree murder.

They also discussed the Oct. 26 fatal shooting of Teresa Ann Bass as she walked with her husband on a footpath in Waldorf. Mebane has been charged with first-degree murder in the Waldorf attack, in which Bass’s husband was also hurt.

Mebane sat mostly motionless next to his attorney during Tuesday’s hearing in D.C. Superior Court, at times staring straight ahead. Bury, also 17, of Baltimore County, covered her face at times, shaking her head and looking to family members behind her.

Tayler testified Tuesday about details Bury supplied during an interview with police. According to the detective’s account, they were staying in a Motel 6 in the District when they ran low on money and planned to rob a cabdriver. Shortly before 9 p.m., Mebane hailed a taxi.

Mebane asked the driver how much a ride to a junior high school near the motel would cost, according to Tayler. Muhammad said it would cost $6.50, Tayler said, and when Mebane asked if he could change a $50 bill the driver said he could.

After Muhammad pulled his silver Lincoln Town Car behind the school in Northeast Washington, Mebane reached into a black bag, put on a glove, pulled out a gun and shot Muhammad once in the back of the head, police said in charging documents.

The car accelerated, crashed into a tree and later burst into flames, police said. Muhammad’s body was found in the driver's seat, Tayler said; he had his wallet, and no money was missing.

Bury allegedly told two friends about the shooting, and they contacted police. D.C. police arrested her and Mebane within days.

After Bury met Mebane on the Web site, she told police, he bragged about shooting Bass — even showing her online news reports about the killing, a composite sketch police gave the media and the 9mm handgun he is charged with using.

Authorities said the pair met in person for the first time Nov. 1.

Family members of both Mebane and Bury did not return telephone calls seeking comment, and nobody answered the door at the house his family rents during a recent visit. A small scarecrow lay facedown on the porch, and a handwritten “No Trespassing” sign hung on the door.

The house is in St. Charles, a planned community 22 miles southeast of Washington, where tree-lined streets are named after animals and mythical creatures.

“We have never had an issue like this,” said Gloria Casiano, who said she was working at the St. Charles community center when police arrested Mebane in the center’s parking lot.

Casiano and others said that Mebane and his family had lived in St. Charles for only a few months and that they did not know him. Casiano did know Teresa Bass and said they frequently chatted at the community pool during the summer.

When Casiano saw Mebane arrested, she said, “I got this big happiness inside, only because they caught the person who took my friend’s life away.”

At Tuesday’s hearing, Judge Thomas J. Motley called Mebane a “danger to the community” and ordered him held in jail until his next hearing. Bury was also ordered to remain in jail until her preliminary hearing, scheduled for Dec. 17.

Assitant U.S. Attorney George Pace said he planned to offer Mebane a plea deal but did not offer specifics.

Mebane was charged via arrest warrant in Charles County; he was already in the custody of D.C. officials. At the time, Charles authorities said they were still investigating that case.