For the family of Nadia Malik, time is measured in the periods before and after Feb. 20, 2014. Before, there was Nadia, a young mother who had ambitions to become a doctor and who wrestled with a tumultuous long-term relationship. And after, in her absence, there is nothing but ceaseless grief and unanswered questions, a raw anguish renewed every year.

“Thinking of what she could’ve become, that’s hard,” her sister Mona Malik said in a recent interview. “I still have moments on the street where I see someone that reminds me of her, and I have this strong sense of, ‘What if?'"

Five years ago this week, Nadia Malik, 22, was found dead inside an abandoned, snow-covered car on 30th Street in University City. She’d been missing from her home in Delaware County for 10 days.

Bhupinder Singh, the father of her children and the last person to be seen with her, was in Ohio, where he told police he and Malik had gotten into an argument about their relationship before he left the state.

In the years since, Malik’s family filed a civil lawsuit against Singh, hoping that would compel him to provide more answers. He never responded to the suit.

A half-decade later, the Maliks still know little about Nadia’s final hours. It is a mystery that confounds them.

“Not knowing what happened, that’s by far the hardest part,” Mona Malik said. “Yes, we still want justice, but we also want a sense of closure. Somebody has to know something, and maybe five years is how long it took them to realize that they need to talk."

In 2014, the Philadelphia Medical Examiner’s Office ruled the cause and manner of Malik’s death “undetermined," an uncommon ruling that raises more questions than answers. But that hasn’t deterred the family in the pursuit of information about what happened to her.

The family hired a forensic expert who said Malik’s death was “extremely suspicious,” possibly a homicide. They retained a private investigator in hope of drawing attention to a case that has frustrated investigators in Philadelphia and Delaware County, where the couple lived. And they offered a $100,000 reward for information leading to an arrest and conviction in connection with her death, a pledge that still stands.

Attempts to reach Singh, 30, were unsuccessful. Mark Phillip Much, the lawyer who represented him on a charge of violating probation in a DUI case by traveling to Ohio in the days after Malik went missing, declined to comment.

The family’s final contact with Malik’s longtime boyfriend was days before her body was found, when he sent them a string of antagonizing text messages, demanding money in exchange for information about her whereabouts. The couple had been traveling around the city and its suburbs in a black sedan owned by Singh’s father. Her body was later found in its passenger seat, covered with a duffel bag.

In 2016, Malik’s family sued Singh, contending that he “intentionally harmed [Malik] and left her dead or near-dead” in the car, abandoning her without her identification, cell phone, or even the keys to the vehicle. The suit also blamed Singh in the sudden and mysterious death of one of the couple’s three children in 2012, a 3-month-old who the medical examiner said died under “suspicious but inconclusive” circumstances of a type of muscle atrophy commonly called “wasting syndrome.”

In the absence of any response to the allegations contained in the lawsuit, a Philadelphia Common Pleas Court judge issued a default judgment in July and ordered Singh to pay the Malik family $10 million to compensate for their loss.

“If I saw him face-to-face today, I don’t think I could compose myself enough to have a conversation with him,” Mona Malik said of Singh. “There’s some kind of connection that no one is putting together, but I think, I hope, one day it will be put together.”

Stephen J. Cina, a forensic pathologist the family hired to review Malik’s autopsy, called the circumstances of her death “extremely suspicious.” Cina found that one of two conclusions could be drawn: that Malik died of “homicide by unspecified means," or, as the city medical examiner ruled, that both the cause and manner of her death were “undetermined.”

Despite the family’s years of lobbying for a second forensic examination by the medical examiner, James Garrow, a spokesman for the city’s Department of Public Health, said there was not enough new information for the office to reopen the investigation into Malik’s death.

That decision frustrates the family. It ignores, they say, the threatening text messages Singh sent Malik’s family as they searched for her. It clashes, in their minds, with evidence that Singh left Malik in Pennsylvania, then traveled by bus to his parents’ home in Ohio, carrying her cell phone and the only key to the vehicle in which her body was found.

Mona Malik is working with Kevin Ryan, a Philadelphia-based private investigator, to try to bring new momentum to the investigation.

“At the five-year anniversary, we now have a second set of eyes on the case, to finally attempt to bring justice for Nadia,” Ryan said. “I think the evidence is there, we just need to present it in a comprehensive way."

The family learned that a man matching Singh’s description was a frequent user of Paltalk, a video chat program, and sometimes discussed Nadia’s death with other users in 2015 and 2016.

One woman gave the family screenshots of a conversation she had with the man she believed to be Singh. In the conversation, he asked her if she was talking to him in order to collect the $100,000 reward the Maliks have offered for information about her death. The man also wrote that he’s “missing Nadia” and that the two “broke up 2 months before her death,” according to the screenshots.

As the family continues to pursue leads, they have an ally in Barry Williams, a retired Marple Township police detective who was involved in the investigation early on.

“As a high-profile case, it is the most frustrating case I’ve had — just the fact that we couldn’t bring closure to the family,” said Williams, now a security official for the Marple Newtown School District. “There’s only one person alive who can answer all these questions for us. And we don’t have those answers."

Williams questioned Singh in 2014 when he was arrested for violating his probation by traveling to Ohio, and said he provided a “brief timeline” of his whereabouts that was later debunked by surveillance footage and cell phone records. Then he stopped talking and asked for an attorney, Williams said.

The Philadelphia police detectives assisting in the investigation said their work was hampered in part by the “undetermined” ruling from the medical examiner.

Capt. John Walker, who worked on the case as a lieutenant in the department’s Southwest Detective Division, said the department’s findings were thoroughly reviewed by staff at the Philadelphia District Attorney’s Office.

“We had good attorneys review the case,” Walker said recently in his office in Northeast Philadelphia’s 15th District, which he took over as commanding officer late last year. “But without a ruling from the ME, there’s not much we could do.”

It wasn’t for lack of trying. Walker said that the detectives “went above and beyond” in the forensic examination, ordering tests to detect every possible substance — they even tested a little-known theory that an overdose of nicotine can be fatal. Nothing conclusive came back.

“All we want to know is what happened,” Walker said. “We’re hoping [Singh] does the right thing, comes forward [to provide more information] and gives us some idea.”

In the meantime, Malik’s parents work to mend their fractured family. The couple won custody of their daughter’s two surviving children, 9 and 5, after a lengthy custody battle with Singh in which a Delaware County judge ruled that they would be better off with their maternal grandparents.

Mona Malik said her mother, 61, did not anticipate having young children back in her home. But it’s a responsibility that ultimately helped her.

“A part of her needs to do it, because she sees my sister in the kids,” Malik said. “It keeps her going.”